The night before, when Harry, Remus, Severus and Sirius had talked to Dumbledore by Floo, the Headmaster had told them he would visit them the next day. They hadn't yet finished breakfast when Dumbledore's head appeared in the fireplace by the dining area of the sitting room.

"Gentlemen, I would like to talk to you. Can I come in?" he asked, his eyes twinkling.

"Of course, Albus," Remus replied. "Come and have tea with us."

Dumbledore stepped out of the fireplace and greeted everyone with a wave of his left hand - the right one looked blacker and more shrivelled than ever. Remus pulled out a chair for the Headmaster, who sat down.

"Milk? Sugar?" asked Sirius.

"Just sugar, please."

Sirius poured a cup for Dumbledore, adding plenty of sugar. Severus looked impatient, as usually happened when Dumbledore was around. Harry was just curious.

"Excuse the earliness of the hour, but I have just received a call from the Giants asking for a meeting. I shall meet them in two hours. I have to go; you know how complicated our relationship is with them. So I had to advance our meeting."

"We understand," said Remus.

"Hmm, I have already had breakfast, but I will try one of these muffins, if you don't mind."

Remus smiled. "Please help yourself!"

Dumbledore took a muffin and had a bite. Then he sipped his tea.

Severus was clearly becoming nervous. "You came to talk about the Ravenclaw Horcrux."

"Exactly. Since Fortescue's and Ollivander's disappearances, a few months ago, I've been following a course of investigations that I hope will prove to be fruitful. I'm afraid I shall have to tell you a long story..."

"We're here to hear you, Albus," said Remus.

"Very well. Everything began in the 40s, when Tom Riddle finished Hogwarts and went to work at Borgin and Burke's. At that time, Mr Ollivander and Mr Fortescue belonged to a traditionalist group that defended the idea that the Wizarding World should revert back to the medieval ways."

"I've heard about this group," said Sirius. "I think my father was a member of it, for some time. The Medieval Traditionalists."

Dumbledore nodded. "Indeed. I heard about that too."

"Oh, my father always wanted to be the most conservative of the conservatives!"

"Black, your father's ideological affiliations are not in discussion here. Let the Headmaster proceed," Severus snarled.

Sirius frowned. "Snape, out of respect for Albus, I shall refrain from expressing my thoughts."

Dumbledore choked back a laugh. "I don't have to be a Legilimens to read your thoughts!" The old wizard shook his head. "As I was saying, both Fortescue and Ollivander were fascinated by the history and the practices of medieval wizardry, and studied them in depth. Curiously, Tom Riddle frequented the same circles as they, and must have been a member of the Medieval Traditionalists. Riddle, Ollivander and Fortescue used to meet in the Hog's Head after work. My brother Aberforth, who works there as a barman, told me that there was a rumour, at that time, that the three of them had located the esplumeor of Rowena Ravenclaw in the Great Glen. Soon afterwards, Riddle disappeared and only resurfaced as Lord Voldemort. Apparently, Ollivander and Fortescue have not spoken to him since."

"What's this ex-plum-er thing?" asked Harry

"Esplumeor. It is the name given to Merlin's place, which has never been found. No one knows exactly what it means. It seems that originally it meant 'cage'," Severus explained.

"So Rowena had an esplumeor, like Merlin?"

Severus arched an eyebrow and looked inquisitively at the Headmaster.

"So it seems," said Dumbledore.

"Do you think that the recent disappearance of Ollivander and Fortescue has any relation with their activities at that time, and with Rowena's esplumeor?" asked Remus.

"This is the mystery we will have to solve," Albus replied.

"From what I heard, Fortescue's Ice Cream Parlour was totally destroyed. Ollivander's was left untouched, but Ollivander has never been seen again. That seems to suggest that Ollivander disappeared of his own will," Sirius observed.

"We have no clue. Our only hope is to find Ravenclaw's esplumeor," stated Dumbledore.

"But where should we begin?" asked Harry.

Dumbledore flicked his wand and a chest appeared on his lap. "Here in this chest I have stored the most important books on Rowena Ravenclaw I could find in Hogwarts' Library. I intended to do this research myself, but the present circumstances force me to move around a lot, and time is more precious than ever to us."

"We will do the research," stated Sirius, determined.

Dumbledore nodded. "I shouldn't like this new task to hinder Remus's contacts among the werewolves, though. He should stay as long as possible among them."

"No problem," said Harry. "Sirius and I will do the research."

Severus gave him an offended look.

"Er, Severus too," Harry added.

"Certainly, but Severus must be available to respond to Riddle's calls," Dumbledore remarked.

"And to prepare Remus's Wolfsbane," Sirius added.

Severus rolled his eyes. "Call me when you have finished deciding my schedule, won't you?"

Dumbledore stood up. "The tea and the muffins were delicious, but I have other less pleasant assignments."

Dumbledore left, and Remus too. Sirius and Harry took the dishes to the kitchen while Severus opened the chest to have a look at the books.

When Sirius and Harry came back from the kitchen, Severus had placed all the books, about twenty of them, on the table and was browsing one of them.

As soon as he saw them arriving, Severus got up. "I'm going to the shed and start preparing the Wolfsbane."

"What're you going to do with that book?" asked Sirius.

"I'm going to throw it into the cauldron, Black."

Sirius pulled a face at Severus. "Don't let the book distract you, or you might make some mistake."

Severus pretended not to have heard and turned to Harry, "Wolfsbane is a demanding potion, but there are moments when there is nothing to do besides waiting. I shall benefit from those moments to read the book and take notes."

Severus left to the back of the house. Sirius opened a cupboard and produced a couple of parchments and quills. Harry sat at the table and started to browse one of the books.

At eleven o'clock Sirius went to the kitchen to prepare lunch while Severus and Harry practised joint magic. The Wolfsbane was tranquilly resting in its cauldron, according to Severus, and would not require attention for a couple of hours.

After lunch, Severus returned to the Wolfsbane. Harry and Sirius spent the day reading and taking notes.

At five in the afternoon, Sirius served tea. Harry went to the shed and took Severus a tray with a cup of Earl Grey, toast and jam.

In the evening, when Remus returned, they had dinner.

This routine was repeated over the next two days. On the third day of research, the Wolfsbane was ready; Remus drank a glass as soon as he arrived home. On the following night the moon would be full.

On the following day, Severus joined Sirius and Harry in the sitting room. While Sirius and Harry read at the table, Severus read on the sofa. Remus arrived before the evening, drank his Wolfsbane and went straight to the shed. Sirius said goodbye to Harry and went after Remus.

Harry sat beside Severus on the sofa and looked at Severus with longing eyes. "They're going to stay in the shed. Can't we sleep together tonight?"

"We made a promise," said Severus.

"But... I can't take it any more. It's been four days and you haven't even let me touch you."

"Do you think it's easy for me?"

Harry couldn't, wouldn't accept that situation. "What we did promise was that we wouldn't touch each other while we were inside this house. What if we go elsewhere?"

"Have I told you already that you should have been put in Slytherin?"

Harry pretended to be offended, but he couldn't help smiling. "Does that mean you agree? Why don't we go and take a walk on the beach? I'm tired of being indoors."

"What if Black comes back and doesn't see us? He will be concerned."

"I didn't know you cared about his feelings..."

Severus made an impatient gesture. "I don't care a whit about Black's feelings. What concerns me is the commotion he may arouse."

"We can write him a note."

Sirius helped Remus to undress, so that Remus's clothes would not be torn when he transformed.

"So, how was your day?" asked Sirius.

"Today I had the certainty that Louis is wavering. I'm almost convincing him that Voldemort is not a solution for our kind."

"And I'm almost beginning to feel jealous of this Louis. You are so enthusiastic about him, and you spend all the time with him..."

"Don't be silly. You know that this is just my job."

Sirius smiled. "Now this isn't true either. You believe in what you're doing."

Remus sighed. "Unfortunately, you're right. This is the worst part. When I think of what might happen if I fail..."

Sirius embraced his lover, who was stark naked now. "Shh. Don't think of stupid things."

Remus let out a sound between a moan and a howl. "It's beginning."

Sirius felt a shudder running through Remus's body and knew the time had come. He held Remus against his body so that he wouldn't be hurt during the painful transformation process.

Soon soft fur sprouted under his fingers, and Sirius stroked it tenderly, feeling the wolf relax and hearing his pleased rumble.

The dark blue sky was spiked with stars, although many stars were overshadowed by the full moonlight. The white waves rolled over the sand, and a light breeze stirred the air. It was almost midnight.

A moment of perfect beauty: the sky, the sea, the sand under their feet, the breeze bringing the salty scent of the sea with it. Severus's body pressed against his, hands squeezing his buttocks. His own moans joining Severus's.

Severus's scent. The texture of Severus's lips, the taste of his mouth.

Tenderness and passion blended in their caresses. They stayed there for a long time, only kissing and touching each other's bodies. The world seemed to have disappeared. There was only Severus and him. There was neither hurry, nor violence.

Slowly, their hearts beating stronger and stronger, they moved together, in a tantalising dance. There was a reef a few feet behind them. Severus pushed Harry and pressed him against it.

Severus lifted up Harry's robes to touch his skin, warm hands stroking over Harry's chest, tracing the lines of his ribs and teasing his already swollen nipples. Harry was hard and breathing heavily. Severus ground Harry into the wall, wedging a thigh between Harry's and moving his hips sinuously, thrusting their cocks together in precise movements. Harry closed his eyes when Severus slid a hand down between their bodies to stroke his cock with sure, gentle fingers. Severus captured Harry's lips again. Moaning into Severus's mouth, Harry pulled Severus's robes up, slipped a hand inside his underpants and found Severus's cock hard and wet.

Harry opened his eyes again to see the moonlight bathing the pale, slender body that fit perfectly into his. Severus was so beautiful.

"Severus... let me see you touching me?"

Severus pulled back a little and held both cocks together. Harry looked down, in awe. Severus's fingers played over the tips, mixing their fluids and teasing. Both moaned together, sharing the same sensations. Harry's finger joined Severus's, gathering their combined essences and taking it to his lips, then to Severus's. Severus licked the wet digit with an enraptured look.

Severus thrust harder against Harry, rubbing their cocks together in a demanding rhythm.

Harry embraced Severus's, wanting to merge his body with his lover's, and felt the spasms of pleasure shooting through his body as they came together.

In the morning, when Remus woke up looking utterly exhausted from the pain and the effort of the transformation, Sirius embraced him. Sirius dressed his lover and lifted him in his arms to carry him to the bedroom.

Snape was still sleeping on the sofa when Sirius crossed the sitting room. No sign of Harry.

Arriving in the bedroom, Sirius laid Remus on the bed, lay down beside him and pulled the blankets up over their bodies. "Sleep again, love. You must rest."

Remus fell asleep again. Sirius waited until he was sure that Remus was deeply asleep; only then did he get up and went downstairs to prepare breakfast.

After breakfast, Sirius, Snape and Harry gathered in the sitting room to discuss their findings - Sirius and Harry sat on the sofa; Snape in an armchair.

"How many books do we still have to read?" asked Sirius.

"Three," answered Harry and Snape in unison.

It was becoming more and more usual; in the beginning, Sirius would be annoyed when Harry and Snape spoke at the same time, but now he was starting to become accustomed to the idea that his godson and his nemesis had a special relationship and shared their magic and even their minds sometimes.

"Why don't we talk about what we have found out so far and see if we have any solid clues or not? The books contain more or less the same information, and I couldn't find any direct clues."

"I'm afraid I have to agree with you, Black. It's always the same story: Rowena Ravenclaw was born in the Great Glen, in Scotland. She was still very young when she met Helga Hufflepuff. The two witches became close friends. A few years later, they joined Salazar Slytherin and Godric Gryffindor to found Hogwarts. She was very intelligent and creative and prized students who had the same virtues. She was the creator of the castle's ever-changing floor plan."

Harry sighed. "Yeah. That's it. I haven't found anything different from that."

"Let's divide the last three books among us and finish this nuisance of a task," said Snape.

The book assigned to Harry, Hogwarts, The Founders, by Aloysius Pensick, contained the biographies of the four founders of Hogwarts. Which meant that Harry had to read only about a quarter of the book, the part referring to Ravenclaw. And he was finishing it when...

"Hey, there's a leaf missing here! The final leaf of Rowena's biography!"

Severus and Sirius stood up and approached Harry, one on each side.

"Let's see... 'At the end of her...' It's true!" exclaimed Sirius. "The rest of the sentence is missing."

"It goes from page 52 straight to 55," Severus remarked.

"There's something wrong here. We have to find another copy of this book somewhere," said Sirius.

Severus wrote the title and the name of the author on a piece of parchment. "I'm going to Flourish & Blotts. Now."

Severus came back three hours later, tired and empty-handed. The search in Flourish & Blotts had had no result. Severus had gone also to Obscurus Books, who had published the book a few centuries ago, but they had informed him that the last edition had been sold out half a century ago and that they didn't have any copies in the warehouse.

Dismay fell upon them. Harry had finished reading the book Severus had left unfinished and hadn't found anything new there either; the same could be said of the last book Sirius had read.

Remus, who looked in good health again and had joined them in the sitting room, frowned. "Sirius... you've said your father was a member of the Medieval Traditionalists..."

"Do you think he could have a copy of this book?" Sirius stood up and paced the room, nervously.

Severus went to the fireplace and threw a pinch of Floo powder into the flames. "Dumbledore's office, 12 Grimmauld Place."

Harry approached Severus and saw Dumbledore appearing into the flames a few seconds later.

"Severus! To what do I owe the pleasure?"

"Albus, there is a leaf missing in one of the books you have left with us. We believe another copy might be found in the Blacks' library. Could you verify this for us?"

"Of course! Can you tell me its title?"

"Hogwarts, The Founders, by Aloysius Pensick."

They waited for Dumbledore expectantly. Severus stood by the fireplace, static. Remus sat on the sofa. Sirius continued pacing the room, with a contemplative look. Harry waited behind Severus, shifting from one foot to another.

Finally, Dumbledore's face reappeared into the flames. "Here it is." Dumbledore handed out the book to Severus.

While Severus thanked Dumbledore, Sirius took the book from his hands and quickly found page 54.

"Sirius, bring it to the table so that we all can see it," asked Harry.

Sirius did as Harry asked. The first thing Harry read was a poem that was quoted in a footnote.

Then he returned to the beginning of the page, where there was just one sentence.

life, Rowena Ravenclaw retired to her esplumeor, in the Great Glen, where she remained until her death, in 1033.

There was an asterisk at the end of the sentence leading to the note attributing this information to the mentioned lines of the poem L'Aquila, by Winnoc of Worthen.

Harry tried to understand the meaning of what he had just read. "So this is the description of the place where she lived. It must be a place with a tower. She was probably an Animagus, and transformed into an eagle."

Severus shook his head. "But the indications are too vague! There must be trillions of rowans in the Great Glen."

"Hmm... The description seems to follow the way from her house to the Great Glen," said Remus in a hopeful tone. "Therefore, if we start in the Great Glen, we will have to find a linn - 'linn' is the Gaelic word meaning 'waterfall'. There must be dozens of waterfalls there too. But near the waterfall, there must be a green lake. Perhaps there aren't many green lakes there. As for the red scaur, well, a scaur is a steep bank of earth... It shouldn't be hard to find it. "

"We will have to go there to find out," stated Sirius. "The problem is we don't even know what we're looking for. I mean, I know we want to find Rowena's esplumeor. But when we find it, what are we going to look for there?"

"I was thinking about it, and had an idea," said Remus. "Tell me if you think it makes sense: so far, we know that the Hufflepuff Horcrux is a cup, and that the Slytherin Horcrux are the locket and the ring. From what Dumbledore told us, Voldemort wanted to make a Horcrux with Gryffindor's sword. Now, those are the Tarot decks. The cup is Cups; the sword is Swords. As for the locket and the ring, well, I don't think it would take a big stretch of imagination to consider them Pentacles. Following this logic, the Ravenclaw Horcrux must be something related to Rods."

"Blimey, Remus, this is brilliant. But what from Rods?" asked Harry.

Remus gave an enigmatic smile. "We can't be sure, but why not Rowena's wand?"

"I suggest that we Apparate to the Great Glen tomorrow morning and began the search," said Sirius.

"We would go in two pairs and take our brooms with us," Remus suggested. "One pair would start in Inverness, at the northern end of the Great Glen, and would go south; the other pair would start in Fort William, at the southern end, and would go north. The pair that finds a waterfall with a green lake in its environs will send a Patronus to the other pair, and we will all gather again."

"Perfect. I'll go with Harry," said Sirius.

"Nonsense. I can protect him better than you," Severus snarled.

"Hey, who said I have to be protected?" Harry complained.

Severus looked at Harry as if he had been deeply insulted, and Harry could clearly read the message "If you choose him instead of me, you can forget I exist" printed on Severus's mind. Harry sighed audibly as he tried to convey to Severus the message that he was being an idiot.

"Harry is my godson. I am responsible for him," Sirius insisted.

"Gentlemen, let's not argue about minor points," said Remus impatiently. "It doesn't matter who goes with whom. Most of the time we will be flying over streams and lakes, and one of the two will have to go along the left bank while the other goes along the right."

The next morning, Sirius woke them up at five thirty AM. They hurriedly had breakfast, cast Disillusionment charms over themselves and departed.

At six thirty, Sirius and Harry side-Apparated to the northern end of the Caledonian Canal, where the River Ness flows into the Moray Firth, near the city of Inverness. The sky was blue, with just a few scattered white clouds. A beautiful day.

"We've chosen the worst direction. The sun will shine straight into our faces." Sirius transfigured Harry's glasses into sunglasses and put on a similar pair, which he had produced from an inner pocket in his robes. "You fly along the left bank of the river, and I'll fly along the right bank. If you find a waterfall or a green lake or anything that looks interesting, you call me, and I'll do the same. We can send red sparks with our wands, what do you think? The river isn't very wide, but when we reach Loch Ness, we'll be flying more than a mile away from each other. All right?"

"All right."

They took off, the sun on their left side. The 18 miles between Inverness and Drumnadrochit passed without any incident. When Harry approached Drumnadrochit, he realised it was a populated city and decided to fly at a higher altitude.

A few miles after Drumnadrochit, Harry arrived at the famous Loch Ness. Always flying along the left bank, Harry suddenly saw red sparks coming from his right. Harry joined Sirius, who told him he just wanted to show Harry the ruins of the Urquhart castle. They flew down near the ground to observe the strange, fascinating building with its sinuous stone walls and its four towers.

When Sirius and Harry left the Urquhart castle behind, they parted ways again, but a few minutes later Harry found an area full of waterfalls, and called Sirius. Sirius explained that they were approaching Invermoriston, a village in the middle of the way between Inverness and Fort William, where the river Moriston tumbles into Loch Ness, forming many waterfalls. That forced them to fly together and slower: they had to inspect each one by one, searching for green lakes in the surroundings. In order not to lose sight of each other, they removed the Disillusionment Charm.

They were flying over a birch forest. Harry noticed there were a few rowans - almost all their creamy flowers fallen - interspersed amid the birches.

Suddenly Sirius shouted, "Hold on! I glimpsed a waterfall hidden by trees."

Harry turned and flew back towards Sirius. It was true: there was a waterfall there, half concealed by the trees. The remains of an old mill could be seen beside it, and wagtails, dippers and kingfishers flicked around the area.

Harry tilted his broom and flew up the waterfall to its top. Up there, the stream ran along a plateau of the mountain, surrounded by other mountains and birch trees. Sirius passed by Harry, following the stream. A few feet ahead, Sirius deviated from the stream to follow a canal that branched off it. Harry went after his godfather, and they stumbled into a lake nestled amidst green pines, birches, hazels and rowans. The colour of the lake was unmistakable.

"It's green!" Sirius exclaimed.

"It couldn't be greener!" Harry shouted back, jubilant.

"It's as green as a Slytherin," said Sirius.

"I'll call Severus and Remus."

"Right. While you do that, I'll search for that bloody red scaur."

Harry cast his Patronus. While they were waiting for Remus and Severus, Harry took off again and circled around the lake to gain altitude and have a better view of it.

Severus and Remus arrived in less than a minute.

As soon as they had removed their Disillusionment Charms, Sirius shouted from afar, provokingly, "You laggards, I thought you'd be the first to arrive here."

"We would have been, if your wolf friend hadn't insisted on inspecting the waterfalls near Loch Arkaig. I told him Loch Arkaig was not on our route, but he was adamant. This made us deviate from our route and waste our precious time."

"Severus, don't be gloomy," said Remus. "They've found the green lake, aren't you happy?"

Severus ignored Remus and turned to Harry, returning the intense look Harry was giving him. Harry came closer. He wanted so much to hug him... For a moment, they stopped in front of each other, magic flowing between them, oblivious to everything that surrounded them. Harry closed his eyes and felt as if Severus were embracing him.

Precisely at that moment, however, Sirius called them again. "I've found the red scaur!"

Severus, Harry and Remus walked round the lake towards Sirius, who had penetrated into the wood and wasn't visible from where they were.

Sirius had returned to the river and found a place on the left bank where the banks rose into a red scaur, of great height. The river was very turbulent there. Harry thought it must be a terrifying view from up there, on the verge of the precipice overhanging the stream.

"Right. This is the red scaur. Now we just have to find the grey rock," said Harry.

"Let's take off again," said Sirius, mounting his broom.

As he was rising off the ground, Harry observed how Severus handled his broom with elegance. Harry didn't remember having ever seen him flying - except on the day of the Quidditch match that Severus had refereed, in Harry's first year, when the last thing Harry was worried about was Severus's elegance.

Severus noticed Harry staring at him and smiled smugly. They were now above the mountains, flying over the river.

Sirius, who was making loops and steep dives, audaciously approached them by the left, missing Severus by an inch. "Could you please stop admiring each other and pay attention to the terrain?"

Severus raised up his chin. "You are just jealous because Harry is not paying attention to your flamboyant pirouettes."

"Do you like my pirouettes, Snape?"

"Black, if I enjoyed this kind of show, I would go to a Muggle circus."

Sirius looked at Severus with curiosity. "Muggle circuses! They're extinct, aren't they? I haven't seen one of them since I left Azkaban. Did you go to Muggle circuses when you were a kid?"

"I went only once. My father was a Muggle, as you know very well."

"Really, Sev?" asked Harry, involuntarily calling Severus by the nickname he only used when they were alone.

"Yes. Your Marauder friends used to mock me for that. They were pure-bloods, and I was just a half-blood."

Harry gaped. Severus, a Slytherin, was a half-blood, while the Marauders, from Gryffindor, were pure-bloods and mocked him for being a half-blood? The world was upside down.

"It wasn't like that, Harry. Remus is a half-blood too; we weren't prejudiced against half-bloods. But Snape would flip out completely if we called him a half-blood, so you know how it is..." Sirius explained. "Snape wasn't an angel either. He would discover our weak points and throw them back at us."

Remus approached them. "Excuse me, I don't want to interrupt such happy reminiscences, but if this is not a grey rock I am a Death Eater."

Ahead on the right bank there was a mountain that seemed to be made of iron.

"Salazar!" Severus exclaimed. "There are many grey rocks in this area, but this one is impossibly grey. It doesn't even seem natural."

They flew towards the iron rock and landed on its top.

"Here we are. We've followed all the clues we had, and we arrived here. What shall we do now?" asked Sirius.

"Now we need another clue," Severus mused.

Harry looked around slowly and carefully. On one side, the river, from where they had come. On the other sides, mountains and mountains.

"I think we should follow the river," said Harry. "It hasn't disappointed us so far."

Sirius shrugged. "All right. But I think some of us should walk while the others fly. We don't know what we're looking for."

Severus and Sirius went on their brooms; Remus and Harry, on foot.

The sun was high. A mild breeze swept through the birches. Among the birches and rowans, there were pine trees, their stems reddish in the sunlight. They walked on the bare grey stones that covered the stream bank.

Suddenly, an eagle (wide wings, a flash of brownish grey, a fierce eye and a curved beak) flew low in front of them, left to right, and vanished beyond the trees.

Harry stopped. "Er..."

"Let's go after it," Sirius shouted from above.

Harry and Remus mounted their brooms and took off, turning right and flying after Severus and Sirius. The eagle flew to the top of a high mountain and... disappeared.

"There is something up there, on the top of the mountain," Severus announced.

"It looks like a cube," said Harry.

Sirius sped up ahead. "Follow me."