Disclaimer: The Great Mouse Detective is copyright Disney.

In all his years with Basil of Baker Street, Dr. David Q. Dawson had found that their association had taken him to several very dangerous places. A visit to the Natural History Museum seemed like a welcome change of pace.

He glanced over at his companion as they entered the small, hidden side door that would take them below the human museum to the mouse one beneath it. A scientist at the museum had sent them an urgent but vague message that morning about a rather curious problem- something about a bird's egg missing from the museum. "I can't promise anything exciting out of this one," Basil had said, "but it's just odd enough that it could be interesting." That thought had the greatest detective in good spirits; business had been slow recently, which always left the greatest detective in all Mousedom disconsolate. Dawson was secretly relieved at the prospect of a quiet reprieve from the usual adventure.

"Are you Mr. Basil?" a young mouse- the same one who had delivered the message to Mrs. Judson that morning- asked as they entered the museum. It was really an unnecessary question; there were few others among mice or men who wore deerstalker caps in the middle of London. "Dr. Chipman wanted to meet you in the aviary. This way, please." The young mouse proceeded to guide them toward the back of the museum. Basil said nothing, taking in every detail of the museum as they passed, but Dawson didn't need his friend's amazing investigative skill to see immediately see what was wrong- the museum had been open to the public all morning, and the heavy traffic throughout the halls would have obscured a lot of potential clues.

Dawson decided to also have a look around, but where Basil was looking for details, the doctor was content to gaze at the museum's displays as they passed them. They had entered a hall of fossilized lifeforms, and great skeletons of long dead creatures were mounted there- Dawson paused to stare in awe as the toothy visage of one giant monster stared back down at him, its empty sockets seemingly trying to decide whether or not it was hungry for mouse. The name beneath the skeleton read "Compsognathus". Overhead, an equally huge creature soared on skeletal wings, mounted from the ceiling- it had a beak full of sharp, snaggled teeth. The name plate that went with it said, "Rhamphorynchus". Even knowing that the owners of the bones were long dead, Dawson shuddered and hurried to stick close to Basil.

"They are rather fearsome looking, aren't they?" a new voice asked with a chuckle, and Dawson looked up to see an older mouse approaching them. Bespectacled and dignified, his smile couldn't quite hide the worry etched in his face as he crossed the hall to shake hands with both Basil and Dawson. "Dr. Chipman," he introduced himself, "and I'm so glad you could come at such short notice. We have a real problem on our hands, and an odd one at that."

Basil smiled reassuringly. "I think you'll find, my good doctor, that these 'odd' problems are often the easier to solve. 'Singularity is almost invariably a clue', as they say. However, the note that your assistant delivered to us was rather vague- could you start by giving us a fuller account of the situation?"

"My apologies, Mr. Basil- I wasn't in the best frame of mind when I wrote to you after the discovery. Come, I'll take you to the scene, and explain things along the way." He proceeded to lead them out of the dinosaur hall, still deeper into the museum, his assistant falling into step behind. "How much do you know of my work?"

"Not much, I'm afraid. You used to do a good deal of field work in New Zealand, I see."

Chipman raised an eyebrow at that. "Oh?"

"Your gait and manner of movement suggests a certain ranginess of muscle used to long years spent traversing inhospitable terrain. That old powder burn scar on your hand is from the rifle you used to collect specimens. Judging by the curl of your right hand, however, you were forced to retire from it due to the arthritis which afflicted your trigger finger. I deduce New Zealand based on your unusual cufflinks- they are made from Kauri wood, if I'm not mistaken, which is native to there. Am I right?"

Chipman broke into a genuine smile, and for a moment his anxiety seemed to vanish. "I knew I'd picked the right mouse for the job! But that's only half the story. I think some background on our project is necessary."

Having exited the public halls, they'd arrived at the very back of the museum, to a large room bisected by wiring that seemed to have been installed relatively recently. The barred off portion appeared to connect to the outside somehow- a breeze greeted the mice as they entered. The fresh air was pleasant, but the entire room smelled strongly of wild animal.

"As you've also probably surmised, my specialty is birds," Dr. Chipman said. "New Zealand was full of them when I was there. It still is, I suppose, although it may not be for much longer."

"Whatever do you mean?" asked Dawson.

"Species which develop in an isolated region, such as New Zealand, are very susceptible to change, Dr. Dawson, and Imperial presence there has brought nothing but that. With the forests being cleared and European rats and weasels poaching the nests for eggs, a good many bird species are in danger of being lost forever- such as this one." He pointed to a corner of the enclosure, where two brownish balls of fluff were huddled. They appeared to be songbirds, their eyes closed in sleep. One of them, a small feather sticking out of place on its head, draped its wing gently over the other. "These are called piopio birds, the New Zealand thrush, of the North Island variety," Chipman explained, undoing the lock to the enclosure's door and opening it. Instantly both birds were roused, bright black eyes on him as he held the door open for Basil and Dawson. "Do please come in," he said. "They won't hurt you." Detective and doctor both stepped carefully inside to join him.

"Pio?" the bird with the ruffled feather chirped questioningly. Chipman smiled and beckoned it to come closer. "Pio!" it exclaimed, hopping excitedly across the cage to meet him; the other bird followed, though with considerably more self-restraint.

Chipman laughed as the first bird thrust its beak under his hand so that the naturalist could stroke the upturned feather. "This one is the male- his name is Peter," he explained. "The female is Petra. They are, as far as anyone can tell, the last of their kind in all the world."

"You don't say?" said Dawson, regarding Peter curiously, as the bird stared back at him in similar fashion. Chipman nodded as the doctor hesitantly extended his hand for Peter to inspect it.

"When a species declines so drastically," Chipman continued, "the general consensus is that its demise is inevitable, and the only interest it generates is a desire to collect specimens before it becomes extinct. I used to feel much as my colleagues did, until I came into possession of a chick, just hatched, taken from the last piopio nest found in the wild. I nurtured the little bird, who grew into adulthood- that would be Peter, here." He stared fondly at the bird, who was nibbling experimentally at Dawson's coat. "However, an idea also grew within me- what if extinction in the wild was not the end? What if we could preserve, and even replenish, a species by breeding it in captivity? No one's tried it before, but after raising Peter I felt that the species deserved any chance I could offer it. So I used my influence at the museum to acquire Petra and the space to give it a try."

"Yes, yes, very interesting," Basil said disinterestedly. He stared at the mess of twigs and feathers spread out at their feet. "Is this how you found the enclosure?"

"No, I'm afraid the birds became frantic when they found the egg missing, and scattered the nesting material everywhere," Chipman said apologetically. "Can you still find anything out from it?"

"It does make things more difficult," Basil muttered, taking out his magnifying glass. "But not impossible." He began to walk carefully around the enclosure, examining the debris strewn across the floor. Knowing better than to get in his way while he worked, Dawson stood back with Chipman. Peter, however, seemed to find Basil fascinating, particularly his tail, which was carried high and swayed slightly as he walked. The other two mice watched with amusement as Peter followed him around the cage; Petra shifted nervously at the intrusion of her nest site.

"I think he's taken a liking to Mr. Basil," Chipman commented. "He's very acclimated to mice, having been raised entirely by myself since before his eyes were open, although as a result he's never fully learned proper avian behaviors, including flight." Chipman paused reflectively before he spoke again. "It's true that in my younger years I approached natural science the way the others do- with a rifle. It's currently the only way to positively identify a species. Even if it weren't for my arthritis, though, I don't think I could ever raise a gun to a living creature again, especially when that species is in danger of being lost forever. It's my hope that someday we naturalists go armed with cameras, instead, and that photographic proof will suffice in place of a skin. Careful, Dr. Dawson- Petra's not as tame as Peter, and doesn't like to be touched."

"I understand now the importance of this egg," Dawson said, quickly withdrawing his hand from the female bird as her beak opened in warning, "but will it still be viable this long out of the nest?"

"Petra hadn't started to incubate it, yet- the egg won't actually start to develop until then, so there's a chance of saving it if we find it soon." Before he could say anything more, Basil cried out in excitement; all eyes turned to him as he stooped to pick something up from the floor.

"What is it?" asked Chipman.

"Tell me, Dr. Chipman, does the museum employ any weasels?" Basil asked, examining whatever was in his hand more closely with his magnifying glass.

"Weasels?" asked Dawson, suppressing a shudder. While some weasels lived among Mousedom, others chose to live as predators; in any case, they were quite rare in London.

"I don't believe so," Chipman answered. "Why do you ask?"

Basil held up his prize for the others to see- a single, course brown hair. "Fur of this type could only come from a weasel, of the northern variety judging by its thickness." He paused in thought, looking to the far wall where a small hatch had been installed into the wall; it was the source of the room's draft. "How many ways are there into this cage?"

"Only through the main door. The enclosure connects to a small pen outside, but the wiring is too fine for even a weasel to squeeze through. Yet the guards recall nothing out of the ordinary last night."

"I see," said Basil, opening the hatch and sticking his head through to look; it was just as the naturalist had said. He continued to think. "I have a theory of what's happened, but I need more information before I'll be confident in voicing it. In the meanti-" Basil's face suddenly contorted into an pained expression- Peter had caught his tail in his beak. The detective snatched it away from him, glaring at the bird. "In the meantime," he continued, "please let me know if anything new develops."

"Most certainly, Mr. Basil," Chipman affirmed, escorting them out. The strangers gone, Petra approached her ruined nest and trilled sorrowfully; the mice watched as Peter hopped to her side and snuggled against her reassuringly.

"Don't worry, Dr. Chipman," Dawson said confidently. "Basil will get to the bottom of this matter." They bid farewell to the old scientist and started for the public halls.

"Mr. Basil?" someone said behind them after they'd left the bird room. It was Chipman's assistant, who had waited quietly outside of the cage.

"Yes?" asked Basil.

"I heard what you said about a weasel, and it got me to thinking. There's a Mr. Mousescott who donates specimens to the museum from time to time- when he has extras from his own collection, which is quite large. He offered to buy the piopios from Dr. Chipman for a very generous price, though of course he was refused. Anyway, Mousescott himself is a mouse, but he has a weasel bodyguard." The assistant made a sour face. "Dr. Chipman might not think so, but if anyone would do it, I'd bet it'd be Mousescott. What an awful fellow."

"I'll look into it," Basil promised. They continued to walk.

"What do you make of all this?" Dawson asked in a low tone.

"Nothing good," Basil replied. "Though as I said, I need to gather more information before I give my thoughts on the matter. I will say, though, that we're unlikely to ever recover the egg." Seeing Dawson's downcast expression, he added, "But let's look into this Mr. Mousescott and see where it leads us, shall we?"