It was after the death, after the funeral; after the inquest and even after the suspension, which seemed to have gone on forever. It was a Thursday, overcast and cold, though it was still September; and in the lobby of New Scotland Yard, a woman was waiting to see Detective Inspector Lestrade.

Detective Inspector Gregory Peter Lestrade was a lot of different names to a lot of different people: he was Boss, Sir, Guv, Mate, Dad and Son. To Julie, he'd once been Darling and was now Greg. Generally, he was used to answering to 'Lestrade'.

Mary Elizabeth Hooper, on the other hand, was just plain Molly. She was waiting for him at the front desk, beyond which no unauthorised people ever went, up from Bart's on her lunch break. She had a cheese and ham sandwich in a clear plastic box tucked up in one hand, and Lestrade thought it may have been the most depressing sandwich he'd ever seen in his life. Her hair had once held a braid. You could always tell the time by Molly Hooper's hair: she came into work neat and in order, but after about three hours her hair always escaped its bounds and made her look like she'd been caught up in some sort of localised tornado.

"Molly. What can I do for you?"

Over his shoulder he felt, rather than saw, the desk sergeant glaring at him. She clearly thought he had better things to be doing than talking personal business to a woman in a pink knitted jumper and plaid trousers. Though technically back at work, he'd been bumped so far down the first-response list that he'd spent a solid week doing nothing but processing paperwork, both his own and other people's. Paperwork was not Greg Lestrade's idea of a satisfying work day. He almost wished Molly had come to report some sort of horrific crime, just to liven things up.

She seemed in no great hurry to begin. He knew from experience that if he pressed her in public she might turn and walk out again, so he ushered her into a nearby vacant office and shut the door behind them, turning on the fluorescent lights and waiting for them to flicker to life. The room was frigid and obviously hadn't seen sunlight in a long time. To save the awkward pause, he went over and twitched the blinds open. "Molly... Listen, um, we're kind of slammed just now—" This was a lie, as the only slamming anyone was doing upstairs was Thompson slamming the photocopier. "Is this something that can wait?"

She stood in the middle of the room like a guilty suspect, wringing her hands. "I was just wondering," she managed to get out, brown eyes so dilated they were nearly black, "if you've heard from John lately?"

Lestrade groaned in spirit. Should have seen that coming. "Quite recently," he said, gesturing for her to sit down. "He's okay."

"Oh, um, good." Molly ignored the chair he'd pointed to. "I was worried... he... was upset the last time I saw him. Listen, I was wondering, if it's okay, if you could tell me where he is, what he's up to?"

Definitely saw that one coming. "I can't, Molly," he said, folding his arms. "If John doesn't want anyone and everyone to know where he is, it's not my place to go giving out his address. I can tell him where you are, if you want."

"Has he said he doesn't want to see me?"

"No." Lestrade decided not to clarify that over the last few weeks, he'd not known John to refer to Molly Hooper in any way, shape or form. "But he's still licking his wounds, Molly. Not operating on that level right now. Now what I'll do is, I'll give him your contact details—"

"You've given him my contact details."

"Have I?"

"Months ago. He hasn't contacted me. Not once since the inquest."

"Well, I can't make him. I'll let him know you asked about him..." Seeing her expression, he sighed. "Molly, he's okay. Really. And I'm sure he'll be back on the radar once he gets through this whole… thing."

Lestrade still struggled to refer to the death of Sherlock Holmes. Clearly, Molly did too.

"Before he—the night before he—I promised Sherlock." She swallowed hard. "I promised I'd keep an eye on John. He asked me to. I'm supposed to, aren't I? I mean, when you make a promise to someone you have to at least try, and now that..."

Detective Inspector Lestrade was equipped to deal with all manner of gory crimes and sadistic criminals. What he didn't feel equipped to deal with was Molly Hooper when she was about to burst into tears.

"He's going to kill me for this." He pulled out his phone and started searching through the menu with one thumb. "Right. You got something to write this down with, or do you want me to text it to you? If he asks, you didn't get this from me."

It was nearly eight o'clock that evening before Molly was able to make it to the address Lestrade had given her. There had been no answer on the mobile phone for months, and he didn't think there was a landline. She found a dingy flat in a quiet backstreet, where foxes foraged in bins under the weak haloes of halogen street lamps, and other things more sinister rustled among the weeds clumping against the boundary fences. Inside the flat, the lights were on, but all was quiet behind the door and it was a minute or two after knocking before she heard the clink of a security chain and the door opened.

Molly didn't know what she expected on seeing John Watson for the first time since the inquest. What she didn't expect is that he would look so… normal. Not a man in the middle of a nervous breakdown at all; a man who had got up that morning and had a shower and brushed his teeth and shaved and put clean clothes on. He may have lost a little weight, and was soon going to need a haircut. Clean and neat. Looked very tired.

By this time she was staring at him.

"Molly. Hi... sorry," he said, face twitching briefly into what was meant to be a polite smile and didn't quite make it. "Come in."

Although it was getting late John was still dressed, including his shoes and jacket. After three seconds in the flat, she got an idea as to why: it was easily as cold inside as it was out. He went over to the radiator and started fussing with it, muttering something about it being defective and that he was going to speak to the landlord about it.

So far, she thought, he'd barely registered who it was and hadn't really looked at her.

"Tea?" he suggested mildly. "I'll make tea."

Before she could reply, he ushered her into a chair—the only chair in the whole flat, and so rickety she was nervous about sitting on it. She took the chance to look around as he fussed around the kitchenette. There wasn't much to see. A bedsit: hideous brown floral wallpaper and orange carpet dating from the mid seventies. The curtains had plastic backing, like they belonged to the bathroom. They might have done once, she thought. They had jagged tears in places and were spotted with mold, though the rest of the place was in order. A bitter reek of old damp pervaded the carpet, four decades worth of leaks and drips could not be remedied by a simple cleaning job. Aside from the single chair and tiny table, there wasn't much else in the room but a forlorn-lookingb narrow bed in the opposite corner, so close that she could almost have reached out and touched it. Meticulously made, but she didn't think it had enough warm bedclothes on it. Maybe the ex-soldier didn't feel the cold like she did.

When John brought her cup over he sat on the bed, since there were no other chairs. He hadn't made anything for himself. There was a good half a minute of awkward silence, broken only by the clink of the spoon against the cup as Molly stirred her tea.

"So," she said, trying to speak brightly. "Not seen you in a while."

He seemed to be considering this. "No... I guess not."

"I've missed you. I tried to call, but I think maybe you've changed your number since… I mean, I kept getting no answer, that's all."

"No, well. I… uh."

Molly had the right number, and had never really thought she had the wrong one. She flushed in embarrassment; not only her embarrassment, but John's. He was looking at the carpet, the ceiling, a nearby lamp and just about everything available to him except her face.

"How've you been keeping, John?"

It was the wrong thing to say, or perhaps the wrong tone. If anything, the room suddenly became even colder. "Fine," he said. "I'm fine."

That was Thursday. On Friday, Molly dropped in to see John on her way back from a grocery trip, bringing a few random items. The wrong thing, again, but she left satisfied that she'd sooner have John offended than going without basics like coffee. On Saturday morning he wasn't at home, which gave her pause: Mike's? Harry's? The cemetery...? Sunday she was at Baker Street to see Mrs Hudson, and that night she was back at John's with a casserole she'd been instructed to give him. He was offended, but he accepted it. Monday was a busy day and she did not make it out to the little bedsit. Tuesday evening she came back, making sure that Mrs Hudson's as-yet untouched casserole was actually served and eaten. Wednesday she brought more groceries. John made tea for both of them this time.

Thursday night she did not go to the flat. She had an important errand to attend to instead.

If Molly looked out of place at New Scotland Yard, she looked absurd at the Diogenes Club, amid velvet carpet and mahogany fixtures. As if aware of this, she spent barely a minute under the pitiless glare of the electric chandeliers and then retreated to wait things out. She did not have to wait for long; within a few minutes Mycroft was leaving. He barged through the foyer and down the front steps in his usual businesslike way and would have walked straight past Molly, but for one timid little plea in the darkness: "Mycroft?"

He turned, alarmed; then he recognised her, even in the dark shadows she was standing in. "Miss Hooper."

Mycroft Holmes: the only person on earth who called Molly 'Miss Hooper', and, she felt, he always made it sound like an insult. Molly had only met Mycroft a handful of times, but she found this unnerving. She found the man himself unnerving. He had always been polite, but he had a way of looking at her as if he could read her mind and what he could read displeased him.

"Hello," she said, pulling at her ponytail.

"How can I help you?" Evidently, 'hello' was not on Mycroft's list of standard greetings.

"Can I talk to you, please?"

For a second Mycroft looked as if he was going to ask Molly to make an appointment with his secretary for the following week. "I'm very busy at the present, Miss Hooper, is this—"

"It's urgent."

Another sigh. Mycroft was making a noble effort not to roll his eyes. "Very well," he said. "Would here suit you? We can talk in private."

It was a chilly night, and she gratefully got into the back of the car Mycroft had waiting. The chauffeur, without being asked, got out of the front seat and walked around to the rear of the car as Mycroft got in and shut the door with more drama than necessary. "I assume this is—"

"Have you seen John lately?"

"Ah." Mycroft seemed to consider this, examining the handle of his umbrella. "No, I haven't. We did not part on good terms."

"I've been seeing him a bit this week," she said. "I mean… not 'seeing him'… not like… listen. Did you know that he's..." She stopped herself before she could blurt out the crass word for it: poor. "Do you know he's... got limited means?"

"I know he has a small army pension and a sister who is financially comfortable." Now it was Mycroft's sleeve that had become fascinating.

"Did you know there's no heating at his flat? He tried to tell me that the heater was faulty, but I checked the other day, and the stove-top doesn't work either. He's had the gas disconnected. And the rent—"

Mycroft made an impatient movement. "This is all very disappointing to hear, but I fail to see—"

"We need to help him."

"Why 'we'?"

"Because he needs our help. And because we both know Sherlock isn't dead."

Mycroft's pupils narrowed. In the half-light, he looked like a hunting falcon.

"When I said I'd help Sherlock," she said, the words tumbling out in one desperate rush before she lost her nerve, I didn't think... I didn't think it was going to be like this. How long am I going to have to do this for?"

"We're not operating on a schedule. For the present, my brother deems it necessary that he not be found by anyone, and I'm afraid that includes John Watson."

Molly strongly suspected that it was Mycroft doing the deeming, not Sherlock. Mycroft was always thinking about schedules and timetables. Molly had worked with Sherlock for four years before... all that... and if there was one thing she knew about him, it was his utter contempt for the constraints of time. "I'm sure John wouldn't tell anybody he was alive," she offered weakly.

"He wouldn't have to. The man is transparent. James Moriarty was the man at the heart of a network, and that network remains. And while it remains, it would not be safe for John to know anything. Anything at all."

"I didn't know—"

"You said you would help Sherlock."

"I did help Sherlock," she retorted.

"That wasn't an accusation." Mycroft smiled thinly, as if his face wasn't used to it. "But it's no help to Sherlock if your indiscretion unravels everything we've worked so hard for. Nor, may I add, will it do John Watson any good."

There was a long pause. Molly met the challenge of Mycroft's gaze—it was he who broke it. She reached out for the car door, then stopped. "No, I'm going to tell him," she said.

Mycroft sucked in his breath; a dangerous, serpentine sound. "That," he said, "would be extremely ill-advised of you."

"Then do something to help! I told Sherlock I would help John—"

"Then you promised beyond what was in your means to carry out. A man like John Watson is difficult to 'help'." Mycroft was looking carefully at her, as if trying to gauge whether she'd really go through with her threat and whether it was necessary to make one of his own. "Nevertheless, my brother and I really are quite indebted to you," he continued. "I'll make a few discreet enquiries into John's living situation and make arrangements as necessary. You have my word on that."

The only problem with this was that Molly wasn't sure what Mycroft's word was worth. She wasn't sure what her own word was worth.

"And," Mycroft continued heavily, "if you truly have Sherlock's interests at heart, you'll treat this issue with the utmost discretion. It's not only Sherlock who is at risk."

Her heart jackhammered. The most dangerous man in Britain had never been James Moriarty. "What do you mean?"

"Be careful, Miss Hooper."

He gestured to the handle of the car door on her side, and somehow, she found herself reaching out for it and getting out of the car. Dismissed.