He dug through boxes he hadn't even looked at for ages, until he finally found it – a small, brown carboard cube, three inches on a side. He opened it and tore aside a layer of plain brown paper. The watch lay in a nest of more plain brown paper, gleaming dully in the morning sunlight.

"What are you doing?" came a voice from a distance.

He lifted the watch. The pattern on the cover – why hadn't it ever interested him before? It was intricate, complex – many circles intersecting, interlinked, concentric, like a Venn diagram gone mad. It was … familiar somehow. He ran over all the possible associations in his mind, but none of them checked out.

"What is it? Oh, it's a watch," said the voice. "How did he know?"

The strange man in the blue box had been correct. "You have a watch, an old fob watch, that you were told came from some ancestor of yours. It's dull gold, and you think that it doesn't work, but you've never tried to open it, let alone repair it. That's strange, because it has a pattern on it that should absolutely fascinate you. But it doesn't. And I suppose it doesn't matter because you'd never figure out what that pattern means, even though it will be apparent that it does mean something. Well, I'll give you a hint: If you open it up, you'll figure it out." And with that, he had stepped back into the box, and the box faded away with a sort of grinding noise.

He traced the pattern with one finger.

"What are you going to do with it?" the voice asked.

"What do you think, John? I'm going to open it."

And before John could say or do anything, he pressed the release button. The lid clicked aside –

"Sherlock! Sherlock!" John was shaking him.

"Oh, my head … what happened?"

"You opened the watch, and it … it shot you, and you fell unconscious, and – we should get you to casualty –"

"No, John, that won't be necessary," he said. "I'm perfectly fine."

"Perfectly fine, my arse! Your pulse is racing. 160, 170 at least!"

"That's normal," he said. "Don't you see, John? It was a disguise!"

"What was?"

"Still not following, oh, John!" He laughed. "That man – the Doctor – you knew it was him because he had a racing pulse and two hearts, right?"

"Yes?"

"Check mine now."

John felt one side of his chest, then the other. "That's impossible!" he whispered.

"Impossible according to your technological knowledge, not according to ours."

"'Ours'?"

The man John Watson knew as Sherlock Holmes laughed. "Oh, John … don't you see? When I opened the watch, it returned my full essence to me – I feel like I've been blind and had no idea, but now I see, and – "

"You're … an alien?" John exclaimed. "Sherlock Holmes is an alien?"

"Not an alien, a Time Lord, John. And my name is Orlonamaorlion – but if you want to keep calling me Sherlock, I won't object."

"But how did you – I mean –"

"Well, John, it goes like this …