Sherlock..........Who?

The Empty Hearse Part Two

SHERLOCK (voiceover): London. It's like a great cesspool into which all kinds of criminals, agents and drifters are irresistibly drained.

(In the living room of 221B, Sherlock – wearing a red dressing gown over his clothes – has been peering at the wall behind the sofa, and now he steps onto the sofa and begins to stick up maps, notes and paperwork.)

SHERLOCK (voiceover): Sometimes it's not a question of 'Who?'; it's a question of 'Who Knows?'

(Somewhere in London a man in his twenties or thirties with a shaved head is sitting on a park bench eating a sandwich.)

SHERLOCK (voiceover): If this man cancels his papers ...

(Near the bench, a scruffily dressed and rather grubby woman – presumably one of Sherlock's Homeless Network – takes photos of the man on her phone.)

SHERLOCK (voiceover): ... I need to know.

(Keeping a wary eye on the man, the woman sends her photos to Sherlock, and he pins one of them onto the wall.Elsewhere, a woman with a dog on a lead walks through a street market.)

SHERLOCK (voiceover): If this woman leaves London without putting her dog into kennels, I need to know.

(Another homeless woman photographs the dog owner and texts it to Sherlock, who again pins the photo onto the wall. He continues sticking up pictures of people and adding crosses and other marks to the pictures and the map underneath.)

SHERLOCK (voiceover): There are certain people – they are markers. If they start to move, I'll know something's up – like rats deserting a sinking ship.

John, now moustache-free, approaches and goes into the surgery in which he works.

221B. LIVING ROOM.

MYCROFT: All very interesting, Sherlock, but the terror alert has been raised to Critical.

(The brothers are sitting opposite each other in front of the unlit fire, Sherlock still in his dressing gown. We can see a chess set between them. Sherlock sits back from making a move, his eyes locked onto Mycroft's.)

SHERLOCK: Boring. Your move.

MYCROFT: We have solid information. An attack is coming.

(He glances down towards the table between them.)

SHERLOCK: "Solid information." A secret terrorist organisation's planning an attack – that's what secret terrorist organisations do, isn't it? It's their version of golf.

MYCROFT: An agent gave his life to tell us that.

SHERLOCK: Oh, well, perhaps he shouldn't have done. He was obviously just trying to show off.

(Mycroft appears to hold back a sigh.)

MYCROFT: None of these markers of yours is behaving in any way suspiciously? (He glances down again and we hear him makes a move.)Your move.

SHERLOCK: No, Mycroft, but you have to trust me. I'll find the answer. It'll be in an odd phrase in an online blog, or an unexpected trip to the countryside, or a misplaced Lonely Hearts ad.

(He had only glanced down briefly before speaking, but out of view there's a slight click as he moves his piece.)

SHERLOCK: Your move.

(Mycroft glances down briefly before raising his eyes to Sherlock's again.)

MYCROFT: I've given the Prime Minister my personal assurance you're on the case.