John had been wrong, of course, when he'd said the ballet would be interesting. His hypothesis that the music was all Tchaikovsky and Sherlock liked Tchaikovsky and would, therefore, enjoy three hours of emaciated lunatics prancing around in pink tights while Tchaikovsky was slaughtered in the background had proved to be unfounded. Sherlock had made a point of explaining this to John in as concise a manner as possible whilst huddled up in their stuffy box, adding that the lead dancer was clearly having a tumultuous affair with the director and had had a rather heated argument with him between Acts I and II, the evidence of which was more than apparent in the sloppy so-called duet between Siegfried and Odette. His address had not been well-received - perhaps because the director's wife was seated behind them to bear witness to his deductions and perhaps because it was Siegfried and not Odette who had been quarrelling with her husband in the wings. It was hard to say, as the woman had not been courteous enough to explain the direct cause of her ear-splitting sob before she bolted from her seat and tore wailing down the stairs. Sherlock was not believed when he claimed ignorance of the woman's relation to the director, which only convinced him further that he and the good Doctor were spending far too much time together as of late.

Still, John was wearing that magnificent blue shirt, the one he claimed was too tight and about which Sherlock emphatically disagreed. Sherlock found himself focusing on that glorious garment through the hushed berating which droned out the entirety of Act III. He made a mental note to give John a proper thank you when they got home for saving him from the slow disembowelment of the Mazurka. Good man, John Watson. Always reliable.

He was relieved to be back in a cab, John's weight against him as they swept through the rainy London night, John's warm hand on his thigh as he dozed against his shoulder. His arm tightened around John's chest, and he found himself pressing a kiss to his head. John snuggled in closer and squeezed his leg.

'Do you suppose Will's blown up the kitchen yet?' he murmured.

Sherlock smiled, his nose rubbing into soft, greying hair. 'Without a doubt. But it's late; they'll be asleep by now.'

'We ought to find them a proper sitter. I know Mrs Hudson is just downstairs, but…'

'They're fine. She'll keep an eye on them.'

'It seems a lot to ask.'

'I can assure you, there is nothing she enjoys more than chasing after them.'

'Please don't make assumptions.'

'I'm not assuming. She told me so yesterday.'

John sat up, his smile sardonic. 'Did she physically speak those words to you, or are you making inferences?'

'She as good as told me.'

'Sherlock…'

He rolled his eyes. 'Alright, fine. She got choked up when I asked her to watch them, but she might as well have hired a skywriter.'

'That's what I thought.' He settled into the crook of Sherlock's neck. 'We should still do something nice to thank her properly. I'm sure she has better things to do than watch our kids.'

'No, she doesn't.'

'Not the point, Sherlock.'

'I'm only aiming for accuracy.'

John sighed and placed a wet, insistent bite just below the curve of Sherlock's jaw, earning a gasp. 'Shut it.'

Sherlock frowned, forcing his pulse to slow. 'I hate that you found my off switch.'

'And I am so glad I did.' He sat back against the seat with a smile, rubbing Sherlock's leg. Sherlock's jacket buzzed and he sighed in reply. 'If that's Lestrade, it's far too late for you to come out and play.'

'I'm not sure who it is.' He clicked on the text, his brow furrowing. A series of nine pips sounded: three short, three long, three short again. 'John?'

'Was that an S.O.S.?'

'John, you need to look at this.'

'What is it?' He stared at the phone. 'That's the picture on your desk. From when we took the boys to Hull.' His eyes widened. 'If Will is mucking around again, I swear to God-' The phone rang. He could hear John's pulse speed up. He took a deep breath before answering.

'Hullo?'

That clear, sweet voice on the other end of the line, shaking with suppressed tears. 'Hello, sexy.'

His heart stopped. 'Hamish-' The hand on his thigh tightened.

'I was beginning to think you'd forgotten about me.'

He closed his eyes, forcing back the tremble in his throat. 'It's been a long time.'

'I hope you don't mind, but I popped by while you were out. Had a couple of things to pick up.'

Will then, somewhere close by, panicked: 'I'm sorry, Dad! I'm so sorry!'

John's hand tore away from his leg, searching frantically for his phone.

'I like the other one better. He makes such funny noises.'

John ripped the lining of his pocket in his mad dash to seize the phone, fingers flying across the screen as he dialled.

'But this one looks so much like you. I can't wait to play with him.'

'Greg! We need you at Baker Street! Something's happened, something's- Jesus!'

'Is that John I hear? How is your darling toy?' His little voice cracked. Sherlock squeezed his eyes shut at the laboured breaths. 'He looks really good these days. He must love having you around to suck him off.'

'Now, Greg! Please! Right now!'

'Hamish, tell your brother it's alright.'

'Dad, I'm sorry, I'm sorry!'

Tiny lungs coughed around a lump in his throat. That bloody cold. Why didn't he listen to John and drink his Lemsip? 'It's alright, Hamish.' Sherlock forced his voice to stay steady. He doesn't like the way it tastes, always so sensitive to citrus- 'Everything's going to be alright.'

A raspy breath, cutting him like a dagger. 'Don't lie to the boy. It does no good to lie to children.'

He swallowed hard, pushing his voice into his chest. 'Why bother with the boy? We both know it's me you want.'

'How did you get to be so ordinary, Sherlock? You used to be fun. You used to like it when I shook things up.'

'You're just distracting yourself. Why not come straight for me?'

A bitten-back sob. His chest ached, unable to look at John, unable to see the tears in his eyes, the blind, bloody, furious panic. 'But you made it so easy. How could I resist?' Another cough, wet and deep. Maybe we can try the blackcurrant kind, it tastes like Ribena, he loves that stuff, we might be able to get him to drink that the next time, he's such a good boy, please, god, just let there be a next ti- His eyes slammed shut. 'I'll be waiting, Sherlock. Ta-ta for now.'

The phone went dead.

John flew out of the taxi before the cabbie could shift into park, racing up the stairs to confirm what they both already knew. A moment later, Lestrade's familiar car screeched around the corner with half of Scotland Yard close behind. Sherlock moved as if he was underwater, reaching the top of the stairs just in time to meet John on his way down from the boys' room: tears streaming down his sheet-white face, eyes pleading, hands shaking. Lestrade bolted up the stairs to them, looking like he'd seen a ghost. His voice sounded a thousand miles away.

'What's happened? John? Are you okay?'

He broke then, sobbed, wept, and there was nothing Sherlock could do, nothing he could change, no way to save the man who'd saved him so many times. 'He's back, Greg, he's back and he has the boys, Mish and Will, they're gone, they're gone-!'

Sherlock sank to the floor, hands knotted in his hair, heart racing and sick. His head slipped between his knees and he heaved and heaved as John fought through his sobs to try and explain, as Lestrade directed the incoming crowd to send out descriptions, alert Special Services, get Mycroft on the phone, as Mrs Hudson ran up the stairs in only her nightgown, panicked and frightened and How could they be gone? Where did they go? Oh god, how did I not know? Oh god, John, no! He closed his eyes and played it again, over and over in his mind: their sweet, shy boy trying so hard to be brave for him, brave enough so Will could be brave, too, brave like Papa so Daddy wouldn't be scared.

He didn't hear the phone calls back to the Yard or CSI trooping down the bedroom stairs. He didn't uncurl from his place on the landing as Mrs Hudson patted his head, madly asking if he wanted a cup of tea before trundling off without a response. He missed the consoling words from Donovan, the panicked look from Anderson, Lestrade's blessed assertion that they clear out already and help with the search.

Then John's hands were on his wrists and easing his fingers from his hair.

'You have to come back, love.'

'He has them-'

'Come back to me, love.'

'John, he has them, he has our boys-'

'I need you, sweetheart, look at me-'

'Hamish has a cold, he was coughing, he was-'

'Sherlock.' A rough palm on his cheek, warm and steady. Tears in John's eyes, threatening escape, anxiety at his brow, shirt untucked, worry worry worry. 'I need you right now. We have to fix this.'

'What are we going to do?'

'You have to shut it off, Sherlock.'

'Shut it off-? John, they're our-'

'What did you tell me? About Mary? I know you remember.'

'He's got them, John-'

'You have to, love. Shut it off. For just a moment, you have to shut it off.' Sherlock closed his eyes. 'We have to find them and you're the only one who can.' Sherlock blinked up at him, teary and shaking. 'Just now. Just for a moment. We have to find them. "Not in this flat; not in this room." Remember? "Right here, right now." What are they?'

He drew a quivering breath, trying to push down the panic and sick fear that threatened to erupt all over the landing carpet. 'Clients.'

'Just another puzzle, just another one of his stupid, sick games. You've won so many times already. What's one more?'

Sherlock looked into his eyes, beneath the same blind terror he felt bubbling up in his own chest, and there was only trust and certainty, complete confidence in the mad brilliance of Sherlock Holmes. Hamish's voice flitted across his mind once more, the gentle determination to not let the bad man see him cry. Brave like his Papa. His hand found John's against his cheek and he shut his eyes, forcing himself to breathe. He swallowed and opened them once more, clearer and colder than they were a moment before.

'I need to see their room.'

It was a mess, although that wasn't exactly out of place. Books piled high on the right dresser and crammed into the shelves. The burn mark on the window ledge from the rocket incident of last summer. Odd stains along the rug on the left side, the results of experiments gone very nearly right. There had been a struggle: a smashed toy, torn sheets, a fleck of blood on Will's eiderdown. He closed his eyes. John was standing firm in the corner by the door, jaw set, breathing steady. Breathe. Grass stains. Library dust. Hamish's shampoo. Coconut oil. His eczema had gotten so much better the past few months. Liquorice Allsorts. Will was hiding them under his mattress again. Sulphuric undertones - he must be hiding that too, whatever it was, must look into that when things are back to normal. Pubescent sweat. Someone had swiped John's hospital coat - it was the only thing in the house with that particular blend of sandalwood Taylor of Old Bond Street aftershaveand harsh antiseptic. Must have happened when he went up to see Harry, they miss him so much when he's gone. Traces of menthol. Coal dust. Tyrconnell Single Malt. Interesting choice. Some sort of adhesive, so familiar, what is that? It'll come. Steel. Ironwood and skin oil. The worn leather of a sheath.

He'd had a knife.

He turned to the door. Scratches on the frame about halfway up. Fingernails long, gritty. Will had hung on. Something on the stairs, must have fallen from at least five feet up. He grabbed it: a little toy bear from a Kinder egg. Hamish had been over the man's shoulder. Mrs Hudson downstairs, why didn't they scream? He turned to the room again: sticky residue on the post of Will's rumpled bed. That smell - duct tape. Of course. He wet his lips.

'I'm missing something.'

'Talk it out.'

'They knew someone was coming. They had to have, the stairs creak and they've been hearing it their whole lives. William always wakes up when the door opens, he would have known if it was us. Never mind the fact that he can smell a lit fag from a hundred yards away and he knows only madmen smoke on Baker Street. Mrs Hudson's in her room, but he's tough, he's impulsive, he'd think he could stand up to whoever it was.' He stood between the beds, looking between them. 'He wakes Hamish. Doesn't want him to shout when the man gets upstairs. Hamish knows Mrs Hudson might be in danger so he keeps quiet, he's loyal like you. But he's smart, too, he reads, he would tell William to leave us a clue.'

'Will was talking in the background.'

'He was scared.'

'What did he say?' John was at his elbow. 'He's clever, Sherlock, they're both so clever, at least as clever as you. What did he say?'

He plays back the tape inside his mind. '"I'm sorry, Dad, I'm so sorry. Dad, I'm sorry, I'm sorry."'

'What does it mean, Sherlock? Something you talked about, something he read, something he knew you'd remember.'

He raced through the halls of his memory, eyes searching, lips repeating: I'm sorry, Dad, I'm so sorry. Dad, I'm sorry, I'm sorry. The walls came crashing down and he gasped. 'Justin Martyr.'

'What?'

Sherlock was already on his knees, feeling under the mattress. 'Justin Martyr, The First and Second Apologies. He nicked it off of a cleric in Hampstead three weeks ago.' His fingers closed around an old film canister and he tossed it to John. 'Hold this. Don't open it, you don't want to know.'

'Why between the mattresses?'

'It's a safe place to hide and it's close, no one will see you sneak anything under there. He's eleven years old, it makes perfect sense. Ah!' He pulled out the battered book, flicking it open. The title page bore two crimson circles around the letters of the author's name. John was beside him again.

'J and M. Jim Moriarty.'

'But we knew that already. Come on, darling, be clever-' His fingers raked through the pages, landing in A Note on this Translation. Will's spiky handwriting already filled the margins, a mess of graphite in the old print. Red ink glared at him from a hasty scribble among a hundred others. 'Titus Fulvius Aelius Hadrianus Antoninus Augustus Pius.' Two red lines drawn carefully beneath the second-to-last word. 'Augustus.' A name slipped into place. His eyes flashed to John. 'He sent Moran.'

'Moran? Sebastian Moran?'

'Son of Augustus, the late ambassador to Iran. Clever boy!' He slammed the book shut. 'Absolutely brilliant!'

John's voice was near panic again. 'Sherlock, if Moran has them-'

'I know.' He flipped up the collar of his coat before slipping the plastic bear into his pocket. Its weight felt comforting against his chest. 'Call Lestrade. There isn't much time.'