Soon everyone in the castle was talking about Sybill Trelawney's new prophecy, and the weirdest speculations were made both by staff and students. Minerva knew she would have to call a staff meeting to discuss the problem, but first she wanted to talk, not with her Deputy Headmaster, who was her good old friend Filius, but with Severus Snape - who she would have chosen as her Deputy Headmaster, if his marriage with Harry hadn't prevented him from assuming a position that would give him authority over his young spouse.

Minerva welcomed Severus in her office and invited him to sit down.

"Severus, what do you think of Sybill's new prophecy?"

"You know my opinion on Sybill and her gifts..."

"Yes. We've always been of the same opinion with regard to this and many other subjects. Anyway, the situation is a delicate one." Minerva sighed. "Don't forget that two of Sybill's prophecies turned out to be genuine."

"That is controversial. Albus used to say that the prophecy regarding the Dark Lord was fulfilled just because Voldemort believed it," argued Severus.

"At any rate, I'm responsible for the well-being and safety of Hogwarts' students, staff and property. I can't simply disregard a prophecy about a theft. If the theft occurs, I will be crucified," said Minerva, annoyed. "Everybody's saying the Grail will be stolen. You know the symbolic importance of the Grail for all of us..."

"You're right. If the Grail falls into the hands of a Dark Wizard or Witch, he or she may use it to gain followers. We have already gone through this and we know what tragic consequences may ensue! I suggest that we strengthen the protections around the Chamber of Secrets and the Grail Room* ," said Severus, thoughtful.

"All right. That will be done," said Minerva.

"Might I suggest blocking the Room of Requirement as well? We won't feel safe if we don't block the access to that Room. Nearly all of the students are aware of its existence, and the place is becoming a source of disturbance. We should also block the six not-so-secret passages to Hogsmeade that haven't been blocked yet. As for the rest, we should continue to do what we have always done: keep our eyes open and be watchful."

"Perfect. I'll think about other measures to strengthen the security of the castle, especially at night. Can I count on your cooperation, and Harry's, to guard the Chamber of Secrets?"

"You can surely count on my cooperation. As for Harry's, I don't think we should burden him. He has to study for his NEWTs."

"Oh, I don't want to overburden him, Severus, but... he's the only one who can enter the place."

"I'll have a talk with him."

A week later, after breakfast in the Great Hall, Minerva entered her office and walked to her desk to start another day of work. Soon she realised this wouldn't be a normal day, though: the sword of Gryffindor, which used to be in a glass case on a shelf behind her desk, had disappeared.

She looked up at the portraits. "Albus? Dippet? Phineas? Fortescue? Everard? Did you see who took Gryffindor's sword from this room?"

The portraits stared at her with a sleepy and stunned look.

"Minerva," said Albus Dumbledore's portrait, "I'm afraid I can't help you; I haven't seen anything. But don't worry: I'm sure everything will be solved in the best possible way."

She would have to suspend classes and call a staff meeting immediately. After all, only the professors had the password to her office.

The thirteen Hogwarts professors and Minerva were gathered in the Staff Room.

"Ladies and gentlemen," began Minerva, "something very grave has happened. The sword of Gryffindor has been stolen from the Head's office."

A murmur of surprise rose in the room.

"I don' believe this," said Hagrid, shaking his great shaggy head. "Jus' don' believe it. The sword o' Gryffindor. Who'd want ter steal it?"

Then everyone started talking at the same time - except for Binns, who glanced around with a scowl, as if he were the only sane person in a room full of lunatics.

"Please, let's keep this civil," said Minerva. "I called you here because you are the only ones who know - or the only ones who should have known - the password to the Head's office. If any of you have any information that might be relevant to this problem, please raise your hand." Minerva winced when she saw Sybill raising her hand, but there wasn't anything she could do to prevent her from speaking. "Professor Trelawney?"

"The prophecy has been fulfilled! Not everyone here believed it, and the necessary steps to prevent this Fate from happening weren't taken," declared Trelawney.

"If it was Fate," countered Severus, arching up an eyebrow, "I can't see how could we have prevented it. We made a mistake: we thought the prophecy referred to another hallow inside this castle, and we tightened our defences around it. We didn't leave the rest of the castle unprotected, though. What happened here was a breach of trust. The Headmistress trusted everyone who's in this room. Yet, someone betrayed this trust."

"That's precious coming from you, Snape," snapped Vector. "How can you talk about betrayal when many of us still don't know which side you were on in the last two wars?"

"Very true, but Snape is not the only one in this room with a murky past," observed Wyrd, looking at Sinistra, then at Slughorn, Remus and finally Fence.

Rolanda nudged Pomona's elbow and whispered something in her ear. Fence seemed uneasy.

"Let's not lose focus," said Remus. "This is not the time for this kind of debate."

Minerva took the word again. "I haven't called you here to discuss our disagreements and debate our personal grudges. What it matters now is whether you have seen or heard anything that may lead us to the sword of Gryffindor or to the culprit of this theft."

Silence reigned until Vector raised her hand.

"Professor Vector?" said Minerva.

"I don't know anything about this theft. But I consider that a very grave occurrence. In my opinion, the Ministry of Magic should be immediately informed about it."

"I sincerely expect we can solve the problem among ourselves," replied Minerva. "I will suspend classes today. As we have already been doing since last week, only with my permission may people leave or enter the castle, send owls or use the Floo Network for external contacts."

"Oh, what a shame!" exclaimed Slughorn. "I was going to receive a visit by the charming Melinda Bobbin tonight. I don't know whether you know her? Her family owns a large chain of apothecaries...."

Pomona stuck out her chin. "A bunch of vultures, that's what they are. Do you know how much the bloody profiteers charge for a bobotuber? It's daylight robbery!"

"Professor Sprout, Professor Slughorn, I'm sorry, but we must focus on the problem at hand," said Minerva. "Every Head of House will conduct the investigations in a different House. Professor Snape will investigate the Gryffindor House; Professor Lupin will investigate Slytherin; Professor Flitwick, Hufflepuff; and Professor Sprout, Ravenclaw. If that method fails, and if by the end of the day we have not found either the sword or the perpetrator of the theft, I will inform the Ministry."

Minerva saw her plans crumble a few minutes later, when Scrimgeour called her through the Floo Network.

"Headmistress, we were informed that the sword of Gryffindor has been stolen. This is a very grave incident. We will be sending an Investigation Committee immediately to Hogwarts."

Minerva could feel blood boiling in her veins. Someone had spilt the beans. Another betrayal. And now the Minister didn't even ask her permission, he merely communicated his decision to her, as if Hogwarts had to submit to his decisions. "Rufus, I don't think it's necessary to involve the Ministry. It's up to the Hogwarts' administration to solve such problems, and we can very well do that without the Ministry's intervention."

"Unfortunately, we will have to intervene. We have received worrisome information, which has to be promptly investigated."

"What information is that? And what is the source of it?" asked Minerva.

"I'm sorry, Minerva, but this is classified information, and I cannot disclose it."

Minerva sighed. That was an arbitrary action. But what could she do? Confront the Ministry? Perhaps it would be wiser not to antagonise them now. When the Committee arrived, she would try to get more information.

The Investigation Committee was composed of four Aurors, led by Mr Neil Nulligan. Minerva received them with cold politeness and showed them the place where the sword used to be, in her office.

"Hey, you!" Nulligan briskly addressed the portraits. "Were any of you awake when the crime took place?"

"Er... " said one of the portraits in the top right corner of the back wall. "I was."

Minerva frowned. Skocpol wasn't very talkative, but had never caused her trouble. Why hadn't he told her he had seen the culprit?

"Very well," said Nulligan. "And did you see who stole the sword?"

"I did."

"Why, Skocpol... Why didn't you tell me when I asked you? Who was it?" asked Minerva.

An eerie silence hung over the office as the four Aurors and Minerva waited for the skinny, grey-haired old man to reply, "It was... It was you, Headmistress McGonagall!"

"That's not possible!" exclaimed Minerva.

Nulligan narrowed his eyes at her, and then turned to the portrait again. "Describe her actions."

"She entered the office, in the middle of the night. She walked to the glass case containing the sword, lifted it, put it under her arm and left carrying the case. That's all I saw."

"Nonsense," said Minerva. "I don't know what's happening here. I just know I didn't steal the sword of Gryffindor."

"Are you sure it was the Headmistress you saw?" asked Nulligan.

"Why, yes!" answered Skocpol. "I see her every day! It was her."

Classes were restarted, for Nulligan thought it would be better to keep the students occupied as the investigations proceeded. Because the Aurors had to search everyone who left the castle for the outdoor classes, Nulligan asked the Ministry to send two more Aurors to strengthen the surveillance. Minerva was dislodged from her office and residence and had to move back to her old office, which was still vacant on the first floor. The place was thoroughly searched by the Investigation Committee before Minerva was allowed to move into it.

The Investigation Committee comfortably installed itself in the castle - each of its members occupied a private room and an office to perform their work. Moreover, now they were the ones in charge of Hogwarts' communication and protection systems, including the different passwords used inside the castle.

The castle was exhaustively searched for the sword or clues that might lead to the thief. At the end of the first day of investigations, from what Minerva could see, nothing significant had been found. It was a great mystery. Since she had been informed of Trelawney's new prophecy, Minerva had given strict orders that all the brooms in the castle should be kept inside the broom cupboard at night. Every night, Minerva would count the brooms and cast a locking spell on the cupboard. The morning after the theft, all the brooms were inside the cupboard when she had unlocked it. The castle doors were locked by Minerva, too, and by the morning she removed the spell. As for the seven not-so-secret passages to Hogsmeade and the Room of Requirement, they had all been blocked.

Therefore, either the sword was still inside the castle, or the thief had left the castle through a really secret passage, or by unknown means.

In fact, when it was said that the whole castle had been searched by the Ministry Committee, that wasn't accurate. The Chamber of Secrets was inaccessible to them. The Committee had to entrust Harry Potter with the task of searching the Chamber. Harry told them he had inspected every square inch of it, including the Grail Room. According to Harry, everything was in perfect order, and there was no sign of the sword of Gryffindor.

Besides the Chamber of Secrets, there was another place inside the castle that hadn't been searched: the chest of the new Muggle Studies professor, Jonathan Fence. That chest was already famous among the staff and students, because Fence refused to open it. He claimed there was a magic object inside it - an object that granted him special powers, but that, if removed from the chest, could kill everyone in a three mile-radius. Fence didn't let anyone get near the chest, and decided not to leave his quarters in order to watch over it night and day. Fence's behaviour irritated Nulligan, because it hindered his investigations, but the Ministry couldn't take the risk of provoking a catastrophe in Hogwarts. The solution was to keep the teacher under the vigilance of an Auror.

When Minerva was interrogated by the Investigation Committee, she had to run through every detail of her memories. At night, in her private quarters, knowing she wouldn't be able to sleep, she decided to do the same thing again. She took a parchment and a quill from her desk and started to list the suspects and their possible motives, remembering what she had seen and heard the day before.

As far as she knew, only the teachers had the password to the Head's office. And the office itself wouldn't let an intruder in - it had a special seal that prevented that possibility. That fact limited the suspects to the teachers and those to whom they might have revealed the password. Not all the teachers were suspects, though. Hagrid didn't sleep in the castle, and Minerva had seen him and Olympe walking to their hut when Minerva closed the castle front door, at night. Afterwards, Minerva had passed through her office, and the sword was surely in its place. Another teacher who wouldn't have been able to steal the sword was Binns, because he was a ghost. Minerva methodically listed the suspects in alphabetical order, by surname. For the sake of completeness, she included her own name, even knowing she wasn't the culprit.

Most Hogwarts teachers weren't married, or their spouses didn't live in the castle, but there were two spouses who did live in the castle and to whom she had entrusted the password:

Minerva sighed. The inclusion of Harry Potter in the list of suspects made the case even more explosive. The newspapers loved to print sensational stories about the Boy-Who-Lived. One more reason for her to try and remember everything that might help to elucidate that mystery.

What most baffled Minerva was the portrait's claim that she was the perpetrator of the theft. That was preposterous. Obviously, someone had impersonated her. It couldn't have been a mere Transfiguration. A good Transfigurer could reproduce some traits (nose, chin, hair), but not the entire body of a person. Skocpol might not be very attentive, but even so, to Minerva's knowledge there wasn't any extraordinary Transfigurer among the suspects - with the possible exception of Sirius Black. A Metamorphmagus could have done it, but Tonks was the only Metamorphmagus she knew. Even if Tonks were the culprit, she would have to have an accomplice inside the castle - one of the teachers would have had to have told her the password. It was quite a fantastic supposition.

The most probable hypothesis was that someone had used Polyjuice Potion to impersonate her. In this case, the Potions masters, Severus and Slughorn, were the most likely suspects. Severus and Slughorn worked independently - each one had his own classroom; Minerva would have to talk to them separately. However, all the suspects probably knew how to prepare the Polyjuice Potion, if they had access to the ingredients. Obtaining one of her hairs or other personal item wouldn't have been difficult, too: she was always in touch with her staff and often received them in her office.

Minerva tried to remember the conversations she had had with each of the suspects the day before, paying attention to any strange detail that might have escaped her notice previously.

She had spent a long time talking to Rolanda in her office, but that wasn't strange at all - the two of them were friends and fans of Quidditch.

Vector had come to her office to ask her for permission and sponsorship to participate in the MMXI International Arithmancy Conference in Ukraine. Minerva had denied the permission, because the Conference would take place in the middle of the term, and Hogwarts didn't have a substitute teacher for that subject. The students couldn't lose their classes! The Arithmantics should schedule their conferences at times that didn't interfere with the routine of the schools! Vector hadn't liked her decision and had clearly expressed her anger. She was quite a strange witch, but stealing the Gryffindor sword was too drastic a move, even for her.

Severus and Remus (along with Sirius) had been spending their free time taking turns to guard the Grail. Minerva had no complaints on their performance: the Grail, according to Harry, remained where it should be - which was a great irony, considering they had thought it was the Grail that was under threat. Minerva couldn't remember anything strange about Severus's, Remus's, Harry's or Sirius's behaviour. However, a good detective wouldn't automatically remove them from the list of suspects.

Slughorn had given a party in his quarters. Minerva had made a brief appearance at the party to taste the wine - Slughorn served the best wines! Minerva had barely arrived when Sybill, as drunk as a boiled owl, had stumbled on her and drawled something about a meteor that she had seen in her crystal ball. A bad omen, of course. Minerva was seriously thinking of checking Sybill into the Alcoholic Rehabilitation Center of St Mungo for some time: she was becoming inconvenient. As if Sybill weren't enough of a nuisance, Sinistra had pestered her too, repeating her request for new telescopes for the Astronomy classes. Minerva had promised to consider the matter - as she always did. But none of those events represented a disruption of routine: Slughorn always held parties, Sybill was always drunk and foreseeing disasters, and Sinistra was always making impossible requests.

Besides the theft of the sword, there was another mystery haunting Minerva: who had informed the Ministry and, even more puzzling, how? The communications had been totally blocked in Hogwarts as soon as Minerva had known about the theft: the Floo Network was deactivated for external communications, and Filch was watching the owlery to prevent any owl from being sent without the Headmistress' permission.

Minerva was tired and couldn't remember any other peculiar details about the suspects. Deciding that her efforts were useless, she grabbed a book to read in bed.

As the Ministry couldn't arrest Minerva based just on a portrait's testimony, the Committee let Minerva reassume her duties as the Headmistress. However, because the Head's office was under strict vigilance and no one besides the Aurors was allowed into it, she had to remain in her old office, with no access to the school's files.

The investigations proceeded; all members of the staff were interrogated, kept under vigilance and had their lives scrutinised.

In the afternoon of the second day after the theft of the sword, Severus entered Minerva's office without asking for permission. She didn't scold him, because she understood he had wanted to take advantage of a moment when she wasn't being watched.

Severus closed the door and approached the desk where Minerva was sitting. "Harry told me Slughorn prepared the Polyjuice Potion in class a week ago. Slughorn told the students that, although that potion had already been taught in the sixth year, it was necessary to revise it, because this potion is one of the favourite NEWT topics. Slughorn left a cauldron full of Polyjuice Potion in his Potions class, without any protection, for the whole week. Anyone could have filled a bottle with it and added the personal item later."

"Severus, have you been running a personal investigation of the case? I'd rather not have you involved in this."

He cast her a piercing look, as if telling her he wouldn't let her down. "I have to go. I'll let you know if I find anything," he said, pivoting on his heel, his cape swirling behind him as he left the office.

Minerva couldn't help smiling. Severus was a loyal friend.

The fourth day was marked by some intriguing news: in spite of the fact that the place was being constantly and closely watched, a water lily had appeared in the Head's office the night before. The beautiful flower kept hovering still in the air, near the place where the sword of Gryffindor used to be. The members of the Investigation Committee had tried to remove it from there, but they didn't succeed. It seemed that a Permanent Fixed-Positioning Charm had been cast on it. The Auror on duty had been so scared that he had asked to be released from his position. None of those events had been reported by the Committee; yet, everyone in the castle was discussing them in detail. The rumours seemed credible, from what Minerva observed, because the Ministry had indeed replaced the Auror with two others.

On the fifth day, a new rumour spread through the castle: notwithstanding the enhanced surveillance, a medieval helmet had appeared in the Head's office, beside the water lily. No one could remove it from there.

Minerva went to the Armour Gallery, on the third floor, and noticed the absence of a helmet. She notified Nulligan, who admitted the appearances of the water lily and the helmet. Nulligan was extremely aggravated; according to him, everyone was talking about those appearances, when the members of the Committee, who were the only ones who had witnessed the events, hadn't mentioned them to anyone.

Another rumour that circulated in the castle that day was that Sinistra's father had been one of Grindelwald's supporters, and that she might be associated with Dark Arts groups. Minerva was caught by surprise, but she reflected that Albus probably knew that when he had hired her for the position. If Minerva could enter the Head's office, she would ask Albus's portrait about that. Since she couldn't, she just mentally took note of the new information. An association with Dark Arts groups wasn't enough to explain the events. No one could explain, for instance, the appearance of those objects in the Head's office. Minerva didn't like the sound of that. In fact, she knew someone who could enter the Head's office at any time. But it was a person she didn't want to suspect.

On the sixth day, Saturday, the rumour that ran through the castle was that a plume had joined the helmet in the Head's office. The mysterious appearances were the only topic of discussion in the castle corridors.

In the afternoon, Filius knocked on Minerva's office door. She invited him in. He stood on his feet, and she didn't ask him to sit down: he was too short, and if he sat down, she wouldn't be able to see him with the desk between them!

"You look worried," said Minerva, encouraging him to talk.

"I was wondering... The fellows of the Investigation Committee changed the password of the Head's office and didn't tell it to any of us. How can those objects appear inside it?"

"That's what everyone is wondering. Have you got a theory?"

"Well... You know very well that, under certain circumstances, it's possible to become invisible..."

"Oh, Filius, I've never mastered such a skill! Albus had this gift, but I don't know anyone else who can do it."

"A wizard or a witch in possession of an Invisibility Cloak could eavesdrop on the password and use it later to break into the Head's office."

Minerva frowned. "The only wizard we know that possesses one... is above suspicion, isn't he?"

Filius sighed. "I suppose you're right. Forgive me for bothering you with my useless conjectures."

"Oh, don't be disheartened. We're all anxious. Let's go to the kitchen and see if they can make us a cherry syrup and soda!"

Filius flashed a hopeful smile. "With ice and an umbrella?"

On Sunday, the seventh day since the theft, even the house-elves were talking about the beautiful tapestry, depicting a lake with a boat on its shore, surrounded by willows. The tapestry had been hung on one of the walls of the Head's office. Rumours were Nulligan himself was guarding the office when the tapestry had appeared, but he hadn't been able to catch the criminal.

A meticulous search of the castle conducted by the Investigation Committee and witnessed by Minerva revealed that the infamous tapestry of Barnabas the Barmy teaching trolls in tutus to dance had disappeared from its usual position, on the seventh floor. Caught between amusement and bemusement, Minerva had to hold back laughter.

Nulligan didn't show the same energy and arrogance of the first few days, and could be heard grumbling in the corners, "What can this mean? Could it be a terrorist act by an anti-troll group? Or perhaps a group prejudiced against ballet dancers?"

Professor Fence still adamantly refused to release his chest; at night, he put it under his bed. Minerva had entrusted a house-elf with the task of taking his meals to his chambers, and had divided his classes between all the other teachers with some knowledge of the Muggle world.

In the evening, Minerva knocked on the door of Nulligan's office, and was received by one of his assistants - a red-nosed, corpulent and cheerful man called Tadg Fortescue.

"Good evening, gentlemen," said Minerva, approaching Nulligan's desk. "You have been in Hogwarts for seven days now. Have you made any progress?"

Nulligan let out an audible sigh. "It's a rather intricate case. I was just commenting to Mr Fortescue... Mind you, it's not just the sword. We've got a water lily, a helmet, a plume, a tapestry... Unless someone's trying to play a trick on us, I can't see how to put all of these elements together."

"And I was respectfully disagreeing," said Tadg Fortescue, a lively gleam in his dark eyes.

"Really, Mr Fortescue? Do you have a theory?" asked Minerva.

"Oh, yes. Those elements have something in common. A water lily is usually on the water's surface, right?"

"Right," said Minerva.

"Likewise, a helmet is usually on a head; a plume is on a bird, and a tapestry is on a wall," stated Fortescue, triumphantly. "Am I right?"

"Indeed," said Minerva, not knowing what to think.

Nulligan seemed to be losing his patience. "Tadg, go straight to the point."

"Water, head, bird and wall. The entrance to the Chamber of Secrets is a sink with a snake scratched onto the tap. Why, it seems obvious that the sword of Gryffindor is hidden in a sink with a bird head tap fixed on a wall."

Minerva struggled not to laugh. "Quite ingenious, Mr Fortescue, quite ingenious... But why would the criminal give us clues to the sword's location?"

"Oh, if you knew how many criminals like to challenge the Aurors with riddles!" exclaimed Fortescue. "You wouldn't believe it!"

"Fortescue definitely has a point in this regard, Headmistress. There are many criminals who like to provoke and challenge the Aurors. They are so obsessive about it that they end up being caught."

Minerva was tired. "Gentlemen, so far you haven't given me any explanation for your presence at Hogwarts. When you arrived, there were four of you; now there are seven. Yet, I can see no practical results from your investigations. My staff and my students are tired of being interrogated and searched. If this case is not solved by tomorrow evening, I'll complain to the Minister and demand your immediate removal of your Committee from Hogwarts."

In the night from Sunday to Monday, Minerva was awakened by a horrible noise. It was like a thunderbolt piercing her soul. First she thought it had been a nightmare, but then she felt her bedroom walls still shaking from the sound. She got up immediately and, still in her nightgown, opened the door.

Remus was approaching her quarters, coming down the corridor. "Please come with me, Minerva. We're gathering the staff in the Head's office. Severus has something very important to say."

"Wait a minute."

Minerva put on a cloak over her nightgown and followed Remus, both annoyed and intrigued.

When they arrived in front of the gargoyle, on the seventh floor, Filius, Harry, Wyrd, Fence, Rolanda, Vector, Sirius and Sybill were already there, and Severus was arriving with Pomona, Sinistra and Slughorn.

"Headmistress," said Severus, looking excited, his hair falling down over his face, "please follow me. I will explain everything when we enter your office."

"But... we don't know the new password!" replied Minerva.

Severus stood before the gargoyle and said:

"Rhombus."

The gargoyle moved aside, and all the teachers stepped inside and onto the spiraling staircase.

The fact that Severus knew the password left Minerva even more concerned.