"Look, I know this sounds like I'm pulling your leg, but I know George. He's very curious about things, and he gets into trouble as often as not, but he's not the sort of monkey to go around stealing jewels." The Man with the Yellow Hat blushed suddenly, "Well, not without trying them on and wearing them around the house, anyway."
John nodded, too enchanted by the sight of a small monkey imitating Sherlock's every move around the burgled flat and making small squeaks of enlightenment to echo Sherlock's deeper "aha's" now and then to pay proper attention.
"I'm sure Sherlock can figure it out," he said, achieving the proper soothing tone by rote. Across the room, Lestrade was pinching his nose, whilst Sergeant Donovan was tugging on his sleeve and muttering something about cages and leashes. John just wanted a camera.
"If George doesn't... oh, no." The monkey, looking up at Sherlock for inspiration, had seen something that Sherlock, looking down at the floor for clues, hadn't noticed, and now it was tugging at his coat, chittering happily until Sherlock frowned. For a moment, detective and monkey stared into each others' eyes, communing on some level that John couldn't even guess at.
Then Sherlock smiled. "Really?" he asked George, reaching down a long hand. George took it and swarmed up to the detective's shoulder, and then held up his arms as Sherlock lifted him even higher. It took both of them to reach the light fixture, but George had it unscrewed in a heartbeat, and then diamonds were falling and bouncing all over.
While Scotland Yard scurried to pick up the expensive debris, Sherlock brought George back down to cradle in his arms while George made mournful, apologetic noises over the last few diamonds in the curve of the lightshade. The Man with the Yellow Hat darted over to them, with John trailing behind. "Now how did those get up there?" he asked.
"When we find the person who brought a ladder in here, we'll know," Sherlock said. "One of the maintenance people, probably the electrician, who'd be able to retrieve the diamonds the next time the light bulb failed -- long after anyone would be looking for them." He glanced around thoughtfully, and then smirked, "Clever of him to move the rug so that the ladder marks weren't under the light any more."
"No, George, you can't keep them," the Man was saying, as he took the diamonds away from the monkey. "We'll find you a different souvenir of London."
George cocked his head thoughtfully, and then tugged at Sherlock's scarf until it came free. In a trice he had it wrapped around his own neck and was looking up at Sherlock expectantly.
John laughed, "No, not that either," he said, although he could see that Sherlock was fighting a grin. "But we can find one in your size. Come on then, I think it's time for a cup of tea."
"And a banana," Sherlock added, lowering George to the ground but keeping his hand. "Definitely a banana."