The first sign of trouble was the clamour on the staircase. Headmaster Snape, passing by on his way to his office and quarters, turned and started up the staircase, towards the hubbub that was rising at the top.

A knot of students stood around the door to the Ravenclaw tower. The landing was small, yet there were easily twenty students in a mixture of sweaty Quidditch uniforms, school robes, and the mufti that was worn on trips to Hogsmeade. Three were madly typing on their phones, ignoring the Headmaster's glare – his hatred of Muggle technology was well known and phones were banned during school time and meals, but this being a Sunday, the students were in the right and knew it. Not that they cared. There were heated discussions happening, but slowly a circle of silence spread out from where the Headmaster stood as the students noticed him and stopped their animated chatter.

Once there was complete silence, he spoke.

"What is going on here?"

Several students began to speak at once, but he silenced them all once more with a wave of his hand, then pointed at one smaller redhead who looked surprised but pleased to be chosen.

"Lucy Weasley – what is the situation?"

"It's the door, Headmaster! It won't let us in!"

Snape paused for a moment. "I shall not insult your intelligence by asking if anyone has attempted to answer the riddle. Is the riddle unintelligible?"

"No, Headmaster." This from a senior student whose Quidditch uniform and dark dreadlocks were liberally besplattered with mud. "Just unsolvable. Even by our best." She nodded at her companion, who looked up from her phone with a worried expression on her face. "If Raye cannot crack it, I don't know who could, at least within the House. Raye? Any idea?"

"Still no clue. Helen. But I'll keep working on it."

Snape said nothing, but swept through the group and up to the door. There, the brass eagle knocker sat, watching him approach. Finally, it spoke.

"The tumbler does not resemble the blend."

Snape scowled at it, then turned with a flourish of his robes and cast his eye over the group as even more students started crowding onto the stairs. "Ideas?"

There was muttering around the group, then Raye spoke up. "We were thinking of something to do with stone-polishing, but nothing came up."

"It's always bloody rocks with you, isn't it, Raye?" This from Helen, spoken with a smile. "We wondered about street performers, but couldn't think what the blend is. Or possibly very dark coffee being roasted in one of those rotating machines, but nothing seems to work."

"Or a glass of something with two drinks mixed." Lucy added. "Please, Headmaster, may we have a hint?"

"The door does not give out hints, and rarely is there much of a delay in working this out." Snape cast his eye over the group, who were looking hopefully at him. At that moment, the door behind him creaked and opened, and a bleary-eyed very young student stuck her head out, stunned by the group surrounding the door.

"What's all the noise about?"

"Hui! Don't let the door close!" The rest of the students swarmed through, while the small student looked at them in confusion. Finally, Severus came up and held the door while he looked down on her.

"Hui Zu, you have given us a partial solution to the problem."

"I beg your pardon, Headmaster?"

"By being on the inside and opening the door at just the right time, you've given your fellow Ravenclaws a way back into their dormitory."

"Oh." She thought for a moment, then smiled up at him. "May I go to lunch now?"

"Hurry. You'll just make it." He suppressed a smirk as she squeaked and went running down the stairs. Holding the door, he was almost face to face with the knocker, which was trying to pretend it was asleep. It opened its eyes quickly though when he tapped it on the beak.

"The tumbler does not resemble the blend."

"You're not helping, you know." Snape grumbled, certain that the knocker grinned for a moment. Although that was unlikely – beaks do not usually grin.

He walked in and up the stairs, towards the common area. There, several of the students were at a table, writing down possible answers to efficiently go through them. Several had crosses next to them. Severus interpreted (correctly) that they had already been tried and had failed, and was pleased at their inventiveness – scrawled on some of the lines were mixture, refraction and anomaly. Half of the students were madly looking up more information, and the other writing ideas and clues down as they were spoken.

"Helen Thomas?"

"Yes, Headmaster?"

"I recommend that you go and have the shower you were going to have when you first came in. The House Elves will need to soak that Quidditch outfit for some time to get the mud and blood out of it. Overeager bludger?"

The tall girl grinned at him. "Overeager Slytherin blatching beater."

"So I should check in the infirmary for Albus Potter?"

"That's the one. He's good."

"But you're better."

The smile said it all. "I could definitely do with a hot bath, to be honest. But how do we get back in, Sir?"

Raye spoke up. "Short of arranging for people to be inside all the time and to come and open it at the summons … a doorbell to the common room, perhaps? It will only work if there's someone there, though."

"I shall delegate a house-elf to sit inside and open it when asked. But this will have to be a temporary solution. In the meantime, I shall open the question to the school to seek the answer." Severus swept his eyes over the student body there, then clapped his hands twice. A house-elf immediately appeared, clad in a fine apron with lace edging.

"Yes, Headmaster?"

It took but a moment for the house-elf to be given her orders, and instructions to have the elf changed every four hours. There was a great sense of relief that no student would be required to stay in the common room all the time, but the question still remained – what did the door mean? What was the answer?

At dinner that night, Severus stood and told the entire student body the issue. As he sat, he could hear numerous discussions on the possible answers, with variations that even he hadn't thought of. Apparently there was something on the internet that could be related, as well as innumerable synonyms of gymnast, doppelganger and polisher. But none of these seemed to be right. Before long he had a crease in his forehead, and performed all his duties the rest of the night with a grunt and a swish of the robes.

Two days later, the door was still obstinately refusing all the answers that were posited. The house-elves were kept busy clearing the landing as scraps of paper with ideas were cast aside by disappointed guessers. And thrice daily, Severus came to the door to stare at it, numerous possible answers coming to mind. None worked. Finally, on the Wednesday, he gave in to the nagging suspicion that had been trying to get his attention since it had happened. If no-one at the school could help, he would need to pull in someone from outside.

He owled the Ministry of Magic that morning after breakfast, requesting their best puzzle-solver. Chagrined, he included the basic facts – that no-one at the school could guess the solution, and that as a result, Ravenclaws had been blocked from their rooms for three whole days.

So he wasn't surprised when Hermione Weasley knocked at his office door and poked her head in just after lunchtime. He just pretended he was.

"Weasley. I should have guessed."

"I'll take that as a compliment, Headmaster. I happen to be seconded to the Department of Mysteries, and was chosen in a trice. Now take me to this door and I shall see what I can do." Hermione came in and shrugged off her light coat, hanging it on the coat stand by the office door. "And you really should change that password. Anyone could guess it."

She wandered slowly past the cabinets in the room that contained a myriad of artifacts from the foundation days of Hogwarts. From the sword of Godric Gryffindor to a rather battered shield that looked as if it had come from the savannahs of Africa to a delicate porcelain bowl that must be Ding ware, the shelves showed the diversity of styles and cultures that had created the School. Severus watched as she ran her dark fingers lightly over the inscribed lip of an earthenware urn that bore the designs of the Adena culture, then he shook himself to regain his composure, and stood up.

"Not true." He tried to maintain the scowl, but having someone there who might be able to help had lifted a load off his shoulders, and he could not keep up the sour looks due to the relief. "Fewmets is not a common word."

"But it is the main ingredient in the door-opening oil you were selling at that market in Teul when we found you. Did you never wonder how we tracked you down after the Battle?" She let him pass and lead her up to the Ravenclaw tower, but the long climb did not stop her talking. "Selling actual magical potions in a town described as magical was a brilliant cover, but you must have known some of us would come looking for you."

"And by some of us, Weasley, you meant you."

"That's Investigator Weasley, if you insist on being formal."

"And if I don't?"

"Hermione will do quite nicely."

"Hermione. Very well." He affected a look of total disinterest, but it wasn't working. In truth, it would be nice to have someone he could talk to without having to drop the level of the conversation down a few IQ points to have the other understand it. While he had been exonerated for his role in the great Battle twenty-five years before, the fear and loathing he had spent years cultivating had not evaporated as fast as his conviction had. Only a few of the old students and teachers would talk with him, and none had been near for weeks. The new students were more prepared to accept him on face value (and he cherished the trust and respect they gave him), but they were the exception, and every year some of them still believed his reputation as told to them by their parents. It was a never-ending struggle to gain their respect, but usually he could do it, at a cost of much time and emotional toil. To have someone come in who already trusted and respected him was a huge relief. Hermione would be excellent company, whether she wanted to or not. Not to mention that she was more than easy on the eye.

They soon reached the landing in front of the Ravenclaw door, and Severus was not surprised to see the eagle head's eyes slightly open, enough that it could see them coming. Hermione walked right up to the knocker, and tapped it with her finger.

"The tumbler does not resemble the blend."

She opened a clipboard folder she was carrying, and wrote quickly. Severus noted with pleasure the speed with which the door was opened when a couple of students came up and knocked on the dark wood, but he felt it would not do to seem too happy about things.

"I included the phrase in the request I sent. Did you not read it?"

"I did, Severus, and I did you a disservice."

"Oh?"

Hermione smiled, slightly abashedly. "Have you any idea how badly some people describe the situation when they write to us for help? It's a poltergeist, but it's blue. Or I don't understand why this ghost keeps haunting us. No I didn't mention that I'd dug up Grandfather's bones and now keep them on the mantelpiece. Honestly, if people would just think about what they'd done, half my work would disappear. But I should have trusted you, of all people, to give a clear and accurate account of what the facts actually were."

The apology and the praise attached to it sent a feeling of warmth through Severus, one he tucked away to be enjoyed later as he turned back to the task at hand. "Did you come with any ideas?"

"Some," she admitted, "but I will need to work on them for a few days. May I have a room somewhere to stay? I don't want to have to be using the Apparition point every day if I can avoid it."

"Won't your husband need you at home?" He said it, knowing it would cause a reaction, but he was not prepared for what he got. Suddenly he was being pressed up against the wall beside the door, pushed there by a single well-placed finger that was against his sternum in a most uncomfortable manner. Hermione somehow managed to get her face right up next to his, despite their height differences, and her voice was low but as cutting as one of his best ingredient knives.

"Any man who 'needs' me will find themselves discovering the direct use of the Advanced Full Body Bind, the one that lasts for days, and then being dropped in the largest pile of nettles the Forbidden Forest can manage to come up with. I do not appreciate being patronised, insulted, or otherwise condescended to by anyone. Not the Minister, not my ex-husband, and most definitely not you." He felt rather than heard the sound of students' footsteps on the stairs near them, retreating quietly in a manner not expected to draw any notice, and he could not blame them. And it was all his fault.

"Inspector Weasley, I apologise. That was unworthy and unforgivable of me. I … I was in the wrong asking that question."

"You certainly were, Headmaster." Her voice remained as icy cold as the Hogwarts Lake in midwinter, and Severus cursed to himself. He had only wanted to determine whether the rumours concerning her marriage were true, but it seemed that he had simultaneously confirmed that, and yet ruined any chances he might have of making use of the fact, in the same clumsy statement. He silently berated himself, while a quietly furious Hermione went back to the doorknocker, looking all over it and casting a few interrogation spells in the meantime.

After fifteen minutes, she sheathed her wand in the holster she carried on her belt, and opened a pouch. The scent from the pouch was delicious, reminding Severus of sunny days in his childhood when his mother was still alive and his father had work and did not drink so much. Hermione rooted around in the pouch a moment, pulling out a small bottle that glowed slightly in the shadows that started to cover the landing. The light from the bottle was elusive – if asked, Severus would have said it was silvery-blue, but then contradicted himself and said browny-greenshortly afterwards.

The bottle had an interesting effect on Hermione – just holding it seemed to calm her down, and she shook herself slightly before starting to open the bottle. Then she stopped, and turned to Severus. "I have to apologise myself again. Your question was … not polite, but my reaction may have been more heated than I intended."

"You do not need to apologise, Inspector." He shook his head, the dark hair now streaked with grey falling softly around his face. "I was completely in the wrong. I cannot understand what made me so clumsy."

"So true. Lack of subtlety was never your way. I suggest we put the incident behind us and move forward." She went to open the bottle again, then looked up. "But you may go back to calling me Hermione. I think I would prefer it."

So would I. He watched as she gently turned the top of the bottle, and pulled out a slim brush that sparkled with the mixture. The brush did not hold much, and yet there was a clear light coming out from the bottle that cast glimmers across the door. Hermione touched the end of the brush lightly on the tip of the knocker's beak. There was a moment's delay, then Severus was stunned to see the liquid run across the bronze, highlighting grooves and swirls on the metal that had not previously been visible.

"What is that?"

"Revealing solvent."

"What magic does it use?"

Hermione grinned. "The opposite of the Invisibility cloak. Harry was kind enough to let us scan it with Muggle equipment, and while we have no idea how the cloak works, we were able to determine some of the ingredients that give it its abilities. By reverse-engineering them, we – my fellow researchers at the Department – were able to create a liquid that reveals fine details and hidden traces. I still am puzzled, but I have a feeling that the identity of the door knocker is going to prove important."

Severus watched, amazed, as the bright lines spread from the doorknocker in fine tracery outwards across the door. Zigzags and circles became visible, and soon the entire door glowed with a low, pulsating silvery light that outlined stylised birds, strange quadrupeds and flowing geometric shapes.

Hermione's voice was low and breathless. "I had no idea," she murmured. "Did you?"

"No, none." He reached out a cautious finger, and touched one of the lines. It glowed brighter for a moment, the brightness travelling from that point and dispersing through the rest of the pattern. He half-expected some of the substance to remain on his finger, but it was clean.

Hermione took a small camera from her pocket, and proceeded to take pictures of all the patterns on the door. "Where did the door come from?"

"I do not know." Severus was wracking his brains to think where he might have seen those patterns before. "You think the door's origin has something to do with the riddle?"

"Either that, or we might find some way around the door if we know how it works. But it's a very unusual set of patterns. Almost primitive, and yet sophisticated." She put the camera away, and then traced the zigzag that ran along the bottom of an eagle-like shape. "Ravenclaw House was founded by Rowena Ravenclaw, who also chose the location for Hogwarts. I know that much. Of course her daughter, Helena, died tragically, which led to the death of Rowena not long afterwards. And all this happened a thousand years ago. But this door … the patterns…"

"They're not the patterns you would find in Scotland a thousand years ago. They're not earlier, either – not Celtic nor other ancestors. I think they're a little like the Beaker folk, but those people did not have the technology to produce something this magnificent. They had bronze, yes, but not to this quality." Severus ran his hands around the sides of the door, checking the lintel and the frame. "I see no sign that the door was put here long after the House was formed, so it must be contemporaneous from while the tower was being built. We have our work cut out for us, Hermione."

"We do." She packed up her equipment, and slung her bag back over her shoulder. "You always manage to surprise me, Severus."

"How this time?" He let her precede him down the stairs, the better to watch the movement of her hips as she descended.

"Knowledge of the Beaker people? I had no idea archaeology was your interest."

"I have many interests." And watching you has just hit the top of the list. "The grounds here, for instance, have yielded some interesting artefacts over the years. I know of at least one suspected Roman building under the edge of the Forbidden Forest, and I have a suspicion that an Iron Age fort lies under what is now the Lake, covered with sediments but visible from its outline when the water is clear."

"Not the Giant Squid's secret lair?"

He did not reply, but followed her as she passed by the turnoff at the third landing, and continued down to the first floor and thence to the Library. Several students greeted her as they passed, but as this included a great number of the Weasley and related clans, it was no wonder they knew her. The doors to the Library were open, and a number of diligent students were making use of the resources to do their homework. Hermione headed straight to the Reference Section, then looked over it with an exasperated sigh.

"One day, Severus, you will have to digitise the entire place. How am I supposed to look for something by its picture when there's no way to search for that?"

"Digitise the Library!" Severus would have laughed out loud except that they were in the Library and silence was the rule. "Next you'll be suggesting we put the school menus on the Internet for the entire world to see."

She ignored the dig, and placed her bag on the table. "Before I settle in, where shall I be sleeping tonight?"

He bit back his first reply, and wondered what had even made him think that. It was not worthy of him, although the idea was interesting. "I thought perhaps you might like the Arithmancy Professor's rooms. We don't have one at the moment, so the residence is available."

But she did not seem to notice the fleeting look of half-hope that had swept across his face. She was taking books from the shelves and making careful piles of them according to subject. "That will do very nicely, thank you, Severus. Now I have some ideas. …" Before he could wish her luck, her nose was down on the books and he knew she would be lost in them for some time.

"I shall send a house-elf to fetch you for tea, then."

He was rewarded with an absent-minded wave, and felt his expectations subside. Of course she would not be interested in him. She was an ex-student. A younger woman. It was pleasant enough that she treated him like a human being (and took no nonsense from him either), but it wasn't as if she was actually interested.

- - - - - -((()))- - - - - -

By the end of the week, Hermione had decided that the student body of Hogwarts was one of the most neglected resources in the world. She'd known it from the Battle of Hogwarts and the help she'd had then, but their assistance in the research was amazing. Not just the Ravenclaws but every other house had volunteered teams of investigators or support staff. There had been crash courses in speed reading, and others in knowing which channels of investigation to follow. Severus himself was quietly smug about the group of Slytherins who had taken the design elements and scoured art textbooks and design sources on the internet for any clue to do with the patterns.

The major problem was that there were too many clues. They determined that the door had been donated to the School at its construction, but they couldn't find out who had been the mystery donor. The patterns too were confusing. The Beaker People link had, as Severus said, fallen through, as had a possible connection with the Thunderbird of the North American First People and their ancestors. There was a brief flurry of excitement when someone thought there might be a connection with the doors and decorations at Notre Dame cathedral, but when Louis Weasley asked his mother to send a guidebook from that institution, they discovered that none of the dates and styles quite matched.

"One hundred years too late at the earliest." Hermione closed the beautiful book of photographs that Fleur Delacourt Weasley had sent with a note requesting it be added to the school library after the investigations. "We really ought to limit ourselves to sources that talk about the school in the year 1000. Especially early legends."

Severus sipped on the tea the House-Elves had brought. They were getting a little tetchy, though, making it clear that having one of them on constant duty in the entrance to Ravenclaw was keeping them from their other duties. But Hermione noticed that Severus seemed to spend a lot of time just sitting and batting ideas to and fro between them. She found it soothing, and a great stress relief, to have someone intelligent to work with. His ideas were always worthwhile, and he had taken a lot of trouble to overcome the awkwardness from the faux pas of the first day.

"Perhaps that's our problem," he said. "Perhaps we have concentrated so hard on the history of Hogwarts that we've neglected another area that might hold information."

Hermione heard a slight shuffle behind them, and turned to see a rather small Hufflepuff lass looking nervous as she approached. Severus had made it clear that anyone with an idea might come to himself or Hermione at any time that they were in the Library, or leave a note if they were not there. And he knew who every single student was. "Suzanna Datjin, what do you know?"

"If you please, Headmaster, Investigator, I owled my Mum and she said it's not the work of our mob, but there might be another that uses those symbols." The small dark girl shifted from one foot to the other, but was smiling as she did. "She said to tell you that it's not Gadigal or any others of the Eora, but she's sent word to an Auntie in the Yamatji nation and they should be in touch soon."

"That was a rather inspired thought. Thank you, Suzanna. Come over here and let me introduce you to Investigator Weasley." He gestured the young girl over, and she shook Hermione's hand firmly, the two hands sharing the same skin tone.

"Hermione, please. I know that accent. Where in Australia are you from, Suzanna, and what is a mob?"

"It's what we call our groups or tribes, Hermione. I'm from Sydney, and my mother is one of the Elders of the local Gadigal people. My people have been there for thousands of years." Susanna laughed. "It's also the collective noun for a bunch of kangaroos."

Hermione nodded her understanding. "And you have just opened up another line of enquiry, Susanna. I realise now that while the origins of the design may not be from bronze-workers, there is nothing to say that it couldn't be a collaboration between the two."

"Of course!" Severus made a note. "A blend. Perhaps that's what that part of the clue comes from. Susanna?"

"Yes, Headmaster?"

"Twenty points to Hufflepuff."

"Oh thank you sir!" The young girl fair skipped out of the library, her face filled with delight.

"You have made more work for us, Severus."

"But if we needed to do the work to find the solution anyway, it is not more work. Rather, it is an avenue of enquiry." Severus looked smug, and seemed to make a decision. "It's nearly dinner-time. Rather than eat here, could I tempt you to join me at a little brasserie I know?"

Hermione almost turned him down, but the twinge she got in her back reminded her just how long she'd been working on this case, and how little of the outside worlds she'd seen since she came in. It was one thing to be a student at the School, with friends and multiple activities to do, but it was another to be an adult seeing only the dining room, bathrooms, office and library. She didn't have much contact with her fellow students from school days as most of them were busy with children and careers that did not intersect with hers. And besides, she was enjoying his company in a not-entirely professional context as well. "That sounds delightful, Severus. Shall I meet you at the Apparition point in an hour?"

"No, my office. We will need to floo." He stood up and brushed some of the dust from his robes before heading off to the other duties incumbent upon the manager of Hogwarts.

An hour later they were wending their way down narrow winding streets with beautiful whitewashed buildings on each side. Severus had not made clear exactly where he was taking her, and Hermione thought she could see Spanish on some of the signs, although the sun had long since set and the street lighting was not bright. The air was a great deal warmer though than Scotland in November, and the scents drifting out from various eateries was making Hermione's stomach rumble. That plate of sandwiches at lunchtime was too long ago.

They turned one more corner, and she gasped as the road led down to the harbourside. Myriad coloured lanterns were hung along the water's edge, reflected in the water in a tangle of shimmering ribbons of light. Then she spotted a sign that said Rua da Calheta, and she knew. Portugese, not Spanish.

"Where are we?"

"Luz. Lagos, in English." Severus guided Hermione along the path and directed her into a gate with a dolphin over the top.

"I half expected Paris, but this will do very well, thank you." Hermione's eyes lit up at the plates of delicious food, and she had to restrain herself from stealing just a mouthful from one platter that was carried past just under her nose. "But I don't believe this is Portuguese cuisine."

"It's not." Severus turned and spoke briefly to the person with the booking schedule, his Portuguese hesitant and broken yet obviously intelligible to them. Within moments the pair were seated at a balcony table, and a bottle of wine placed between them. "This was where the Portuguese slave trade started so many centuries ago, and as a result, the town has quite the diversity of cultures. This restaurant specialises in South African cuisine, and I have yet to have a disappointing meal."

"But however did you find it? Were you in Lagos for very long?" She cast her eyes down the menu, deciding that the ostrich might not be to her taste but the avocado and biltong sounded delicious.

Severus waved at the sea, which lapped at the waterfront nearby. "I was here for a potion ingredient fair many years ago. As a hub of multicultural trade, there was a great variety to be found here, and a few of us decided to brave the local restaurants in the evenings. We only had to endure one tourist trap before we found this place. Now, may I interest you in the wine?"

Dinner was delicious, and far too relaxing. Hermione found herself leaning forward to hear Severus's voice, thus forcing him to speak softly and rather enticingly. The sounds of the streets came up to their table, with words that were almost intelligible and the occasional sound of strolling musicians. The dishes ranged from exotic to completely unbelievable. Not one disappointed. Or maybe that was the wine, which slid down far too fast. She was surprised when they finished a whole bottle, and declined the offer of a second – she was tipsy but did not want to face-plant on the way home. The bottle was beautiful too, its label consisting of dancing stylised San people figures around the name of the vineyard. She turned it to follow their path around to the back, then stopped as Severus grabbed her hand.

"That was … abrupt!" She winced a little – his grab had not been delicate.

"Hermione, you have the answer in your grip."

"And here I was thinking you were trying to get my attention." He still held her hand, and she wiggled it a little to loosen his grip. Under her fingers, the glass was cool yet not as smooth as she would have expected.

"Let me show you." He gently lifted her hand off, then waved away the waiter who decided now was the moment to clear the table. "Here, on the neck."

There, where her hand had rested, was a shape created when the bottle was first moulded. It was hard to make out in the candlelight and dim bulbs surrounding them, but Hermione, checking that they weren't being watched, slipped her wand out and cast a quiet Lumos, holding it up so that they could both see the design.

It was a stylised bird, haunches strangely bent and folded up in front of it, making it look as if it was sitting back on its haunches. Its long neck held up its proud head, and the back and wing feathers were lightly incised, their texture glittering in the wands' bright light.

More importantly, the design under the bird was a zigzag with dots, very similar to those that ran around the Ravenclaw door.

"South Africa?" Hermione shook her head. "I would never have guessed."

"No, not South Africa." Severus turned the bottle around so that the label was visible to her. "Zimbabwe. It's a Zimbabwe bird, according to the information here, but I know little about it. And what connection could it possibly have with Hogwarts?"

Hermione grinned. "And I have my Handbag of Holding with me. Pass me the bottle – we'll investigate it when we get back. I have enough room for dessert, and that Melktert looks delicious."

Dessert was as lovely as it looked, but they were both distracted, as evinced by Severus carefully putting a spoonful of sugar in his saucer as he lifted his coffee cup to his lips. Hermione was relieved by this – she had almost drunk from the vase in the centre of the table, and had just managed to make the gesture look as if she was admiring the flowers instead. They headed downstairs afterwards, and Hermione took a moment to look around while Severus was settling the bill.

"They have a shop! I need to use the facilities, then I'll be in there." He nodded, and she headed to the bathrooms. Two minutes later she slipped into the side room which was filled with arts and ingredients from the African continent. The range was extensive and bewildering, but she carefully looked along all the shelves, seeking information or any other designs that seemed similar. It didn't help that a great deal of the artwork there was also beautiful and enticing, and she was just considering the wisdom of buying a beautiful silk scarf that had stylised elongated women silhouetted against a glorious sunset pattern when Severus spoke up from the other side of the room.

"The original carved birds are from the ruined city of Great Zimbabwe, which was built by ancestors of the Shona, starting in the 11th century and inhabited for over 300 years." She looked over to see him reading from a large book. "According to this, the original birds were carved in soapstone and stood on columns. Although I don't know how much I trust this book."

"Why ever not?"

"The next part says citation needed. They've copied their text directly from Wikipedia, and not even bothered to check it before publication." He tried to look very serious, but the both of them then broke into laughter, aided by the large amount of alcohol in their systems. "I will say that the picture is very close to our mystery carvings on the door."

She walked over to him and put her arm around him while she stood beside and peered at the pictures. "You're right. But why an eagle? Although the door knocker is an eagle, which I've always wondered about. Raven and Eagle don't really seem the same."

Severus put the book down on the table in front of them, then turned and took Hermione in his arms. "Did I ever mention, Hermione, how lovely it is to be working with someone like you?"

"Always asking questions, incessantly talking and full of useless information?" She reached up and put her arms around his neck.

"Not quite, although I'll accept those as well." Then he reached down and kissed her gently.

The kiss might have gone on a lot longer, except that there was a polite cough from the doorway.

"Senhor e Senhora, estamos nos fechando. Havia alguma coisa que você queria?"

"Eu gostaria deste livro, por favor."

The two disentangled themselves, and Hermione tried to put her feelings back into neutral while Severus took the book to the cash register to pay for it. She joined him as he was collecting the parcel, and felt awkward about what to do now, but he took her hand naturally and tucked it into his elbow to lead her back to the floo point in the old city. She couldn't help thinking how nice it felt, being appreciated, being admired, being …

Kissed.

They climbed up the hill towards the only part of the town that hadn't been destroyed in the 1755 earthquake, and into the laneway that ran to the hidden tiny room with the floo port. The moon had just climbed over the edge of the medieval buildings and was shining down on the cobbles, and as Severus laid his hand on the required tile, Hermione stopped him by laying her own hand on his.

"Hermione?"

She turned him around, and kissed him back, hard. Here, there were no Portuguese mothers to interrupt them, no students to come in at inappropriate moments, not even a poltergeist to drop a bottle of ink on them. There was only moonlight, a medieval laneway in a town made from dreams, and the pair of them kissing.

- - - - - -((()))- - - - - - -

Severus walked Hermione to her rooms, and, checking quickly for wandering students or patrolling teachers, kissed her once more at the doorway before watching her go inside. He considered inviting her back to his rooms, or angling for an invitation into hers, but no, the slower pace was suiting him quite well.

He put the parcel on his desk, then headed to bed, the wine still spinning a little after the long-distance floo. Two large glasses of water later, he was ready to sleep better than he had for a long time.

Unfortunately, he hadn't counted on the eagerness of a certain bushy-headed witch who was hot on the trail. Seven o'clock was his normal waking time, and he had considered sleeping in until eight with all the lovely dreams the previous night had provided. At six, there was a knock on his door.

He opened the door feeling every bit the grumpy bad-tempered wizard that his reputation had been for so many years, to be greeted by a far-too-happy brown-smiling-faced Inspector Weasley.

"Shall we proceed, Severus?"

He may or may not have made a grumbling sound.

She bounced past him to his desk where the book on Great Zimbabwe sat, and lay beside it a copy of A History of Hogwarts. "How long since you read this?"

"Not since the Chamber of Secrets opened. Is there anything useful in there?" He moved up beside her, and peered over her shoulder at the book, noting with pleasure that not only was it her own copy, but that all the pages were dog-eared from long and heavy use.

"I'm not sure." Hermione opened it with a confident flourish to the first chapter, and ran her finger down the page. "But I have an idea." She turned and started, obviously not expecting him to be quite as close as he was.

"And so do I." Severus put his arms around her and kissed her gently. She moved in and responded, showing no signs of remorse over the previous night. And he took full advantage of it. The kiss became more passionate and involved, until she gently pulled back from his embrace.

"I would love to continue that later, Severus, but right now we have work to do."

He sighed gently, and let her go. "So tell me your idea."

"I cannot believe that an institution of such importance as the opening of Hogwarts School happened without some sort of a ceremony. And that ceremony may well have had invited dignitaries from other schools. Perhaps one of them was connected with the Zimbabwe bird."

"Then breakfast, the library, and a solution. Let us go."

"Not quite yet. I need a shower and to get dressed." She stood back, and Severus noticed that she was dressed in flannel pyjamas and a pair of pink fluffy slippers. "And perhaps you should too."

He looked down, and realised the robe he had thrown over his own nightwear had come apart. "Probably. Turning up to breakfast in my best nightgown would give even the Head of Slytherin a start. I shall meet you there." He escorted her to the doorway, then bent and kissed her again. "Later, Hermione."

She almost skipped off, and Severus turned to go back inside, instead glimpsing a passing Hui Zu, whose own eyes were almost as wide as saucers.

"Morning, Hui. Early for breakfast?"

Hui squeaked and ran off, and Severus headed to his rooms for his ablutions.

At breakfast, he sat at the Staff table, and smiled as Hermione walked in with her hair still wet from her shower. He was so distracted by the sight of her figure as it swung past the tables that it wasn't until Professor Flitwick nudged him that he heard the ooohhhs and snickers from the students.

Immediately the rarely-seen-until-recently smile was replaced by the better-known scowl, which instantly silenced the student body. Breakfast was strangely quiet, and the glances he got from Hermione showed she knew it too. He finished his breakfast, then headed straight for the library and the oldest copy of A History of Hogwarts that he could lay his hands on.

For the next hour he sat, pouring through the information on the Founders, the creation of Hogwarts, and the opening of the school. He was oblivious to nearly everything else until a warm hand was laid on his shoulder and a cup of tea was deposited by his elbow.

"I thought you might like this." Hermione slid herself beside him, and put down her own cup of tea. "Any luck?"

Severus glanced up and saw no-one else in the library apart from Helen Thomas and Raye O'Connor. Those two were completely absorbed in flirting that they obviously thought no-one else had noticed, so he risked a quick kiss on her cheek then turned back to the book.

"Not yet, although there are significant differences between your copy of the book and this one." Severus pointed to a picture of the school. While the version in the copy Hermione had showed all the towers and battlements completed by the time the school opened, the version in the older book showed most of them still under construction. But the old magically-moving engraving also depicted a large crowd at the Grand Opening that seemed to be a huge mixture of people from different countries. There was a witch in a Fengguan Phoenix crown from the Tang dynasty, and the phoenix would occasionally take off and fly around her before returning to its perch. One person beside the stage was wearing a wooden mask with moose antlers on it and what looked like tusks out the top, and beside them was someone with a headdress entwined with snakes. As they stamped their spear on the ground, their long elaborate robe undulated in the breeze that must have been present that day. And a part of that robe caught Hermione's eye.

"Look! Zigzags!" She pointed at the hem of the robe that only showed clearly for a second or so.

"You're right. If we find out who he is, perhaps we'll find the secret of the door." Severus turned the page, and snorted. "If only this had been in your version of the text."

There on the page was a circle made of drawings of peoples' heads, with their titles underneath and a line from the name to a small map of the country they came from. The person in the moose mask had come from the northern section of Canada, and a fierce looking Khitan warrior with his own eagle was from the western edge of China. Most noticably, the one who was (as far as Severus could tell) the person who had been wearing the snake headdress and the cloak, was a tall black-skinned bald-headed person with pierced ears, a strange marking on their forehead, and a smile on their face. The country they were connected to, though, bore no relationship to any country Severus had heard of.

"Azania. Do you know it, Hermione?"

"Never heard of it." Hermione traced the country's outline with her finger. "I'm guessing one of the old nations of Africa, but I thought I knew all of them. Azania is a new one for me, although I wonder if perhaps it became part of Tanzania."

"It was, but it was far bigger than that." Helen Thomas had come over to peer at the old book, Raye hovering nearby. "It covered most of the eastern side of Africa from Lake Victoria to south of Kilimanjaro."

"You know this place?" Severus asked. "My father might be a rabid West Ham Fan, but my mother is from Zimbabwe. You did know my middle name is Choni, didn't you?" The girl ran her finger around the outline of the strange country. "There have been wizards and witches in those areas since I don't know when. Oh!"

She pointed at the profile that was linked to the country, and gasped. "Queen Shingai of the Azani people! She was famous – one of our great heroes and such a powerful woman. You don't mean to tell me she was at Hogwarts as a student?"

"No, as a dignitary at the opening of Hogwarts." Hermione was visibly agitated, and Severus was having trouble restraining himself from leaping up and shaking the girl to get every last bit of information out of her. "Could … did Azania have bronze working a thousand years ago?"

Helen laughed out loud. "A thousand? They invented it nearly three thousand years ago! Most of the other areas of Africa went straight to iron, but there was sufficient copper and tin in Azania to support their bronze work for centuries."

"The Britons had bronze two thousand years before that," Raye protested, but Severus waved at her to hush her, and turned back to the tall black girl whose dreadlocks were decorated, he realised, with beads with the same zigzag on them.

"Could the designs on the door be from Azania, then?" he asked. "Or Zimbabwe? We think the patterns bear a likeness to the Zimbabwe bird."

"Possibly. Oh dear. I hadn't thought of that. All this time…" The young Quidditch champion looked crestfallen. "The bird itself comes from Azania."

"What is the name of the bird in your mother's country?" Hermione asked gently, and Severus made a note to ask her afterwards how she managed to keep her enthusiasm under control.

"We just call it the Zimbabwe bird. I know it's also called the visarend, the nkwazi, or the aigle pêcheur." She blushed and smiled. "Mother made sure I knew at least some of the languages from her home."

"Aigle pêcheur? That's French, surely?" Hermione was madly writing them down, and trying to make sense of some of the words. "Fish eagle?"

"Yes, an eagle that lives on fish. Not like the other ones."

"Others?" Severus had a feeling they were homing in on something. "The food-stealing lizard-eaters. The bateleurs." Helen's eyes flew wide open. "That means street performer in French. Tumblers. You don't think…"

"Don't run! Walk! Safety!" Hermione yelled out as the four turned as one and headed for the stairs. "And while we're walking, Helen, tell us everything you know about these birds."

"They're an eagle – and they come from a family of eagles that eat snakes, but they're the only ones that don't. And eagle and snake – that must be the blend. If only … Please don't hate me for not realising." Helen was almost in tears, and Raye stopped her and hugged her hard (and blocked the stairs from the two adults.)

"Don't blame yourself, Mudiwa. It's not that you missed it – it's that it took all the clues to lead here, and you were the one to unlock it." Raye rubbed Helen's back, and then brushed the dreadlocks back from her face and kissed her nose. "If it hadn't been for you, how long would these two had taken to work it out, hey? You're the saviour, not the villain, in this case."

Helen managed to hold herself together, and the two walked up the stairs again, now hand-in-hand. Severus was tempted to take Hermione's hand as well, but she was carrying the large book and had now reached the section where the gifts of the guests were listed. Behind them, a crowd of Ravenclaws started to gather, following in a wave of students as the word flew around that the puzzle might be solved.

"And from the nation of Azania came a door that could only grace the halls of those both wise and clever. The knocker, in the fashion of the hungwe, would charge the students to solve the riddle before allowing them into their tower, thus proving their intelligence to the wizarding world. If I ever find the wretched wizard who edited the later editions, I will be having some words with them, yes I will." Hermione's determined look should have warned the door as they approached, but it seemed that the knocker was really asleep for once. "Thus did the great Queen show her approval of the school which admitted all of great wizarding ability, regardless of their gender or the colour of their skin. And she departed back to Azania, and promised to send her daughters and her daughter's daughters to Hogwarts for the true and frank exchange of ideas. I think that when Salazar Slytherin tried to enforce blood purity shortly after the school's founding, that may have been enough for the Queen to stop sending her daughters here."

"Or she died and the next ruler did not think it important." Severus stood in front of the knocker. "Or there was trouble and unrest in the area. We should look more into the history of magical nations other than just Britain and Europe. But now, I think Helen should be the one to take the honours here."

There was now a huge crowd on the landing and down the stairs, and at the front stood Helen and Raye. Helen walked up to the knocker and tapped the bronze beak with her strong fingers. It stirred, exhausted from all the attempts that had been made to find the answer, then opened one bleary eye and peered at her.

"The tumbler does not resemble the blend."

With a strong, clear voice, Helen spoke.

"Bateleur."

The door creaked open, to the surprise of the house-elf who had been sitting behind it. The elf, Helen and Hermione all went to speak, but Severus held up his hand for silence for a moment. When all were quiet, he spoke one sentence.

"Fifty points to Ravenclaw."

With a cheer, the entire rest of Ravenclaw surged forward, lifted Helen up and swept her up the stairs. The sounds of revelry could be heard starting in the common room above them, and as the last stragglers followed their friends up and away from the landing, the house-elf looked hopefully up at Severus.

"The puzzle has been solved, Dimity. Go and tell the rest of the house-elves that they no longer need to keep the door open."

"Thank you, Headmaster!" The elf disappeared almost immediately, leaving Severus and Hermione together on the stair.

"It really did take teamwork, didn't it?" Hermione held out the book. "And this book needs to be properly investigated.

Severus took it out of her hands, and laid it on the floor beside them. Then he took her face in his hands, and kissed her lightly. "Perfect teamwork. Hermione, would you consider continuing this?"

"You want me to work at Hogwarts with you?"

"And I thought you knew everything, Hermione." He kissed her again. "I want you to make a team with me. For life. Hermione, will you marry me?"

She said nothing, just reached up and kissed him back, and this kiss lasted and lasted and neither of them noticed Hui Zu until she walked up, saw what was happening, and squeaked. Severus stopped kissing Hermione just long enough to say Bateleur so that Hui could get in, then glared at the door. But the knocker was asleep – or pretending to be again.

Africaans: Melktert – Milk Tart

Portuguese: "Sir and Madam, we are closing. Was there anything you wanted?"

"I'd like this book, please."

Shona: Mudiwa - Dear One.

Edited to change the reference from "Bushmen" to "San people", as the former is considered pejorative. Always good to learn new things!