221B Baker Street. The Kitchen. Dinnertime. It's dark outside, but the flat is lit by a homey glow of light. Sherlock, with his jacket off and the sleeves of his shirt rolled up, is at the cooker, frying chopped onions and bacon in a pan. On the other side of the room, something is being warmed up in the microwave. John, carrying Rosie on his hip, is moving around the kitchen table, setting it with plates and cutlery, expertly one-handed.

The table has been cleared of laboratory equipment, and the microscope has been moved aside to allow three people to sit and eat comfortably.

JOHN (to Sherlock): So, I owe Mike Stamford a new computer keyboard now?

Sherlock picks up a pot from the worktop and tilts its contents - spaghetti - into the pan. A hiss rises from it, together with a little cloud of steam.

SHERLOCK: I told Rosie she should have aimed for his tie instead. Destroying one of those would have been a service to mankind. But yeah, the keyboard was inundated beyond repair, I'm afraid. (As if to make his point, he pours a creamy sauce over the pasta, and starts stirring vigorously.) The coffee was already cold and stale, though, so Stamford won't be expecting compensation for that. (He glances a little guiltily over his shoulder at his friend.) I'm sure he wouldn't have placed the mug within her reach anyway if it had still been hot.

John shakes his head, unconvinced. The microwave pings, and John walks over with Rosie on his arm to retrieve a small bowl from it.

JOHN (to Rosie, putting the bowl down on the table): What were you doing at a computer anyway, hmm?

SHERLOCK: They were watching cartoon clips on YouTube.

John's eyebrows go up. Sherlock lifts the pan off the cooker and starts heaping spaghetti carbonara on his and John's plates.

SHERLOCK: Totally age appropriate though, Stamford assured me. Something about a mouse.

JOHN: A mouse?

SHERLOCK: Yeah, the Great Mouse Something-or-other. I forget. She loved it, apparently.

John glances at his daughter and shakes his head again. Rosie smiles broadly back. A fold-away high chair has been placed for her at the table. John puts her into it, then settles down in his own chair, at right angles to his daughter and opposite Sherlock's place. After replacing the pan on the cooker, Sherlock joins them.

JOHN (in a rather rueful tone): I can't do this forever though, can I?

He stirs the contents of Rosie's small bowl - a shapeless orange mash, probably some kind of carrot-based baby food - and then offers a spoonful to her. With a bit of coaxing, she reluctantly accepts it.

JOHN (to Sherlock): Dump her off on you, I mean, or on Stamford, or on the world and his wife, just because I'm running late at work.

SHERLOCK: Well, if you compare the cost of a cheap mass-produced piece of electronics to that of out-of-hours professional childcare, I'd say it's a reasonable arrangement.

John grins wryly. More coaxing, and some more carrot mash disappears into Rosie's mouth. Meanwhile, Sherlock has started picking at his own dinner with an equal lack of enthusiasm.

JOHN (with a nod at his plate): I've never seen you cook spaghetti carbonara. I didn't even know you like it.

SHERLOCK (a little evasively): Well, the bacon and eggs were threatening to go off, so…

He looks up, and realises that John hasn't had a single bite of his own yet, and that his pasta will be cold long before he'll get the chance. Sherlock immediately puts his fork down, and wordlessly holds out his hand for Rosie's spoon.

JOHN (more relieved than he'd like to admit): Oh. Ta.

He hands the spoon over to Sherlock and starts tucking into his own meal. For the next few minutes, Sherlock feeds his goddaughter while John wolves down his dinner, making the best of the opportunity for as long as it offers. There is an almost comfortable silence, until John's plate is nearly empty, and he slows down to finally address the elephant in the room.

JOHN (leaning back in his chair, to Sherlock): So, and while Rosie was having fun with Stamford, you stumbled across Shinwell Johnson dead in the morgue.

SHERLOCK: Well, it would have been more surprising to stumble across him there alive, but that about sums it up.

He wipes Rosie's chin clean with a tissue, then offers her the next spoonful. Rosie turns her face away in protest. The spoon immediately turns into a rocket or a spaceship, and comes humming through the air in a spectacular loop before landing in Rosie's mouth, which has fallen open in wonder while she was watching it approach. She swallows mechanically.

JOHN (unsmiling): You realise we can't keep doing this either?

SHERLOCK (distractedly): What? You'd need a lot of persuasion, too, if you were supposed to subsist on tasteless, shapeless vegetable pulp.

The next rocket takes off, but this time Rosie sees through the trick. As soon as the spoon is within her reach, she resolutely pushes it away. Sherlock shrugs and hands her a small glass of water instead. She takes it in both hands, and happily drenches her bib trying to drink from it.

JOHN: I mean the case, Sherlock. (He nods towards his daugther.) It won't be long, and we won't even be able to talk about ugly stuff like this in front of her any more. Except maybe in code.

SHERLOCK (with a smile): That could be fun. (To Rosie, securing her glass) Come on, no more flooding today. (To John) But I'd have said this case was particularly family-friendly, you know. Even the murderers seem careful to commit their crimes between nine and five.

JOHN (testily): You know what I mean. Or I hope you know what I mean. Seriously, you ask a man to keep watch on a house, and twenty-four hours later he's as dead as a doornail. I find that disquieting, if you don't.

SHERLOCK (in the same light tone as before): D'you want to drop out of this one, then? That's fine, you know. Lestrade's probably right about motorcycle gangs and their tedious turf wars. Sounds like you won't be missing much.

JOHN (crossing his arms): I thought we were looking at chickens and funny stick figures. Now we're looking at a brutal murder. Did you see that coming?

SHERLOCK (with a shrug): No.

He scrapes the rest of the carrot mash from the bottom of the bowl, avoiding John's eyes. John, however, is clearly not yet satisfied with that answer. Eventually, Sherlock meets his eyes again.

SHERLOCK (quietly, but rather gravely this time): No.

JOHN: All right. So how can I keep taking Rosie along, if even you can't tell whether it'll be fun or serious business?

Rosie visibly perks up her ears at the mention of her name. Sherlock makes use of it by sneaking the spoon into her mouth one last time.

SHERLOCK (to John): I told you, I'm fine if you drop out. In fact, I'd probably sleep better if you did.

John frowns in surprise at this unexpected statement. Rosie, miffed that she let herself be taken in, chooses this moment to return that last unwanted spoonful of carrot, by pursing her lips and spurting it all over the table in front of her.

JOHN (exasperated): Rosie, really!

He jumps up to fetch the kitchen roll, and then hastily starts wiping the mess away. Sherlock, unperturbed, collects the bunched-up papers and reaches out with a long arm to drop them in the bin.

JOHN (walking over to rinse his hands at the sink): This isn't about biker gangs, is it?

SHERLOCK (soberly): Of course not.

JOHN: And you knew that straight away.

SHERLOCK: Oh yes. Biker gangs take pride in showing the world who they are. Patches and emblems are an integral part of their subculture. But Johnson's workshop didn't have any decorations of that sort. Nor did his gear, or they'd have mentioned it at the morgue. And that's not surprising, really. Johnson would have been stupid to form an affiliation with any particular club. It would have limited his customer base dramatically.

JOHN (drying his hands on a towel): So that brings us back to The Warren.

SHERLOCK: I'm afraid so, yes.

JOHN (resuming his seat): So Johnson caught André sneaking around The Warren, and André gunned him down?

SHERLOCK (sardonically): And then dragged the body, in heavy biker's gear, all the way down to the Brent Reservoir? In broad daylight? That would certainly have raised a few eyebrows, even in West Hendon.

JOHN: Then what happened? Are you really saying that Johnson's death had nothing to do with the job you gave him?

SHERLOCK (a little snappishly): I'm going to worry about that once I know for sure how and why exactly he met his death, John. But until then, there's no point in wasting any time or energy on that question. (When John doesn't respond, he continues in a kinder tone.) But you're probably not that far from the truth, you know. Yes, we must assume that Johnson died because he saw something he wasn't supposed to see.

JOHN: And what exactly did he see?

SHERLOCK: We don't know that yet. But I'm sure Detective Inspector Lestrade will have the answer for us when he joins us in a moment.

Downstairs, the doorbell rings.

JOHN (grumpily): Show-off.

SHERLOCK (a little wounded): No show. Simple deduction. (To Rosie, raising a finger in a gesture of instruction) Car engine, quite distinctly a BMW, approaching and then stopping at the kerb right outside our house, where only a policeman would have the nerve to ignore the no parking signs. (With a reproachful glance at Rosie's father) Sometimes you'd think your dad's new to this, wouldn't you?

JOHN (not amused): Mrs Warren thought this André guy was a weirdo. Now it looks like he's a murderous weirdo. You tell me what's so funny about that. You said yourself you were worried how far he'd go to protect his woman.

SHERLOCK (with a sigh): I don't expect that André will go anywhere ever again, John.

JOHN: He'll – what?

Before John can put his bewilderment at this statement into words, there are heavy steps on the stairs, and a moment later, Greg Lestrade looks in at the kitchen door.

SHERLOCK (breezily): Ah, come in, Detective Inspector. Did you find the motorbike at the bottom of the Cool Oak Lane bridge?

Lestrade baulks.

LESTRADE: What? (Catching on, annoyed) No, we bloody didn't! Couldn't you have told us that sooner? The search's on hold now until daylight tomorrow.

SHERLOCK (with a dismissive wave of his hand): Well, then you know where to resume it. No hurry. It's probably not his own, anyway.

LESTRADE (sarcastically): Well, that's a comfort.

John, remembering his manners, pulls out the fourth chair from under the table by way of invitation. Lestrade gratefully accepts the offer and sinks down in it, looking weary and exhausted. He summons up enough energy to smile and wink at Rosie on the other side of the table, but the friendly expression slides off his face again as fast as it came.

LESTRADE (to Sherlock): As a matter of fact, forget the motor biker for now. I'm here about Molly Hooper's other guest.

SHERLOCK (in a studiously casual tone): You mean the road accident? I thought he wasn't yours?

LESTRADE: He is now.

Sherlock, not surprised in the least, gives John a pointed look. John's frown deepens.

JOHN: What road -

SHERLOCK (to Lestrade): Well, tell us all about him, then.

He turns to Rosie, who has started fidgeting in her seat and drumming her short legs against the edge of the table. It's making the plates rattle.

SHERLOCK: And you, Miss, promise to let us talk a bit in peace, and you'll be getting some real food.

As if on command, Rosie stops drumming her legs against the table, looking expectantly at her godfather. Sherlock starts cutting the leftover pasta on his plate in small pieces. John watches with his brows drawn together, torn between stopping his friend supplying age-inappropriate food to his daughter and accepting the respite it promises. Meanwhile, Lestrade has taken out his little black notebook to refresh his memory.

LESTRADE (reading from the notebook): The Border Agency's identified that other man in the morgue as one Andrei Ivanovich Zima, twenty-two, from Rostov on Don in south-eastern Russia.

At the mention of the name, John's head snaps up in surprise. He looks from Lestrade to Sherlock, eyes wide with dawning comprehension. Sherlock gives him a sharp look and very quick shake of his head, masking the motion by putting his pasta plate in front of Rosie at the same time. John takes the hint and shuts his mouth again, but he looks less than happy about it. Lestrade flips over a page in his notebook and continues his report, apparently oblivious of the wordless little exchange that has passed between the two friends.

LESTRADE: He entered the country on a tourist visa a little more than a week ago. (To Sherlock) His visa application has all the details your ego could possibly wish to see there. Occupation, painter and decorator. Military service with the Russian navy until the end of last year. Stationed in Murmansk on the Barents Sea. (To John, with a sarcastic undertone) As anyone could have told from the frostbite scars on his feet, of course. And then he comes to London to warm up, only to get run over by a car. (He pauses for effect.) Three times.

There is a silence. John looks stunned, Lestrade resigned, and Sherlock almost indecently satisfied. Rosie meanwhile has started helping herself to pieces of spaghetti, pushing them into her mouth with her whole hand. None of the three men take the time to admire her fine motor skills. Lestrade chucks his notebook onto the table and leans back in his chair.

LESTRADE: That's what Molly found, at any rate. She estimates that the first time the car went over him was bad enough already to break his neck and sever his spinal cord, but apparently someone wanted to make doubly and triply sure he'd never rise from the tarmac to tell the tale. (Wryly) So the guys in Roads and Transport are well shot of him, the lucky bastards. This one's definitely Homicide and Major Crime, too.

SHERLOCK: Where did it happen, and when?

LESTRADE (raising an eyebrow at him): You sure you don't know that as well as I do? Or better?

SHERLOCK (impatiently): Where and when exactly?

LESTRADE: Quarter to twelve, on the corner of Park Road and the A5, or West Hendon Broadway as it's called in that part of town. And yes, thank you, I've noticed that's no more than half a mile from where we pulled the motor biker out of the Brent Reservoir. Guess why I'm here. (He arches an eyebrow at Sherlock.) Add to that the fact that Molly puts the two men's deaths within an hour of each other at the most, and you can count yourself lucky that I'm not getting out the thumbscrews.

SHERLOCK (with a disdainful curl of his lip): And I've been wondering all these years why your interrogations never yield any useful results.

LESTRADE (gravely): I'm warning you, Sherlock. I can't tell what exactly it is you're hiding from me, but I can tell that you're hiding something.

JOHN (quickly, to Lestrade): Weren't there any witnesses? To the accident, I mean? The A5's a busy road, isn't it lined with traffic cameras?

LESTRADE: No, we're out of luck there. There's some major road work going on at the moment, so they've disconnected the power lines - traffic lights, cameras and all. Half the street's blocked, including the pavement, and the locals are avoiding that stretch of road as best as they can. We're thinking about putting out an appeal, but for all we know the street was deserted just when it happened. And anyway, it's not the kind of neighbourhood where everyone's keen on talking to the police about anything.

JOHN: What about the road workers? Didn't they see anything?

LESTRADE: They'd all just gone to have lunch at the local curry shop.

Sherlock gives John another very pointed look. This time, it definitely doesn't escape Lestrade, and it makes him positively angry. He pushes his chair back abruptly, and rises to his feet.

LESTRADE (to Sherlock, in a very disgruntled tone): Well, have it your own way. I just hope you know what you're doing. And in case you end up ready to cooperate after all, you know where to find me.

SHERLOCK (straight-faced): That's my line.

Lestrade rolls his eyes at the heavens, but can think of nothing witty to reply. He straightens his coat.

LESTRADE: Right. I'm off. Gotta get in touch with the Russian embassy – formal identification, next of kin, funeral arrangements… (To Sherlock, still peeved) All the stuff you never need worry about.

He nods goodbye to John, waves half-heartedly at Rosie, who has both her hands in the pasta by now and doesn't even notice, and turns to leave. When his hand is on the door handle, Sherlock speaks up again behind his back, in a suddenly dead serious tone.

SHERLOCK: Don't do that.

Lestrade turns back, surprised.

LESTRADE: Don't do what?

SHERLOCK: Don't contact the embassy. Not yet.

LESTRADE (bewildered): Why not? What's –

He breaks off, seeing the grave expression on Sherlock's face. The two men look at each other for a moment. The cogs are visibly turning in the Detective Inspector's head. Then Lestrade lets out a long, low breath.

LESTRADE: Dammit.

SHERLOCK (in a mock-congratulatory tone): There you are. I knew even your memory couldn't be that short.