When he was five, Hamish had spent a long and painful night in the children's ward of St Bartholomew's Hospital as a direct result of his elder brother climbing onto the kitchen worktop, grabbing the bottle Papa had hidden behind the embalming fluid on top of the refrigerator (labelled 'Do Not Touch This, William Watson-Holmes - I MEAN IT'), and pouring several heaping tablespoons into Hamish's muesli while he was in the loo. As Will would put it later, Papa had 'gone ballistic', shouting loud enough to send the cabbie into a frenzy while Dad rubbed Hamish's back and held the paper bag he chundered in the entire ride over. Will was laid into all over again when Aunt Molly rushed up from the morgue after hearing reports of 'a bloody madman in children's screaming at this tyke'. He stood ashamed while she berated him, stock-still as she demanded, 'Does "at Her Majesty's pleasure" mean anything to you? William Morstan, you look at me when I'm talking to you!' Upon review, they had both agreed that a gutting from Aunt Molly was far worse than Papa's screaming. After all, Papa did that sort of thing all the time.

He didn't think he would ever forget the overwhelming fear he'd felt as he retched for hours into a plastic bowl: the steady assertion echoing in his mind that he was most certainly going to die; Will's white face as he stood terrified in the corner, watching his brother waste away because of what he'd done; Papa racing from nurse's station to paediatrician and back to his room, demanding answers and speaking gibberish. He had hardly believed it when he woke the next morning very much alive and aching from head to toe. Dad was still in the chair beside his bed, working through all of the activities in the colouring book on his bedside table. Papa had only just fallen asleep in the bed next to him, his jacket still on and his brow sweaty. His brother had been exiled to a week with Uncle Mycroft for his indiscretion (Dad had argued a bit at that, he'd learned, stating that there were far more humane punishments for juvenile offenders available in the civilised world). Looking back, it had almost been worth it to have a week alone with his parents, eating all of the jelly and ice cream he could stomach and drifting off snuggled against Papa while Dad met with clients and muttered to the walls.

That had been the worst night of his life. Even after the taste of hot, fetid breakfast ceased to haunt his memory. Even after he and his brother had reconciled and he had agreed that a bottle labelled like that was just begging to be opened. There was nothing that he could think of that would be as awful as that dreadful night in Bart's.

This was indescribably worse.

It was dark and cold. The clammy floor and dusty air were worsening his cough. His shoulders ached against the freezing pole to which his hands were tied. The man in the hat was in some dark corner, his location betrayed only by the red tip of his hundredth cigarette and his infrequent chuckles at Will's asthmatic wheezing. But worse than all of this - far, far worse than any of these terrible, painful, frightening things - was the view directly in front of him.

His brother was crying.

Will didn't cry. Will didn't know how to cry. Will fell out of the tree in Gran's garden and broke his arm in three places and didn't shed a tear. Will nicked half the Aeros from the shop up the street and Papa had Uncle Greg lock him up for the afternoon and he never made a sound. Now Fearless Will, William the Conqueror, his ally, his protector, his ballast in the absurdity that was their life at Baker Street was weeping and shaking with fear, and Hamish felt empty and hopeless inside.

If Will was crying, what chance did he have?

Hamish wasn't brave. Hamish wasn't clever. Hamish read too many books and got jam on his trousers and hated the dark. Hamish hadn't woken up to the smell of smoke outside their window and known - absolutely known - that the man in the hat was bad and mean and hated their father and wanted them dead and they had to do something about it. Hamish didn't have to be good at those things; that's why he had Will. But now it was dark and his pyjamas were thin and Will was crying and Dad was scared and Papa must be scared, too, angry and frightened, and that only left Hamish and he had to think fast or they wouldn't wake up this time, not a chance.

The realisation did nothing to ease his concern.

Will was the hero, not him; he didn't have enough Watson in him for that. They sat in the dark and he could distinguish a dozen kinds of grit on the floor, three species of roaches crawling on the wall, the ages of the rats scuttling overhead. He could identify that the man in the hat smoked Superkings 100s and hadn't bought new trousers in two years and had a wonky knee he pretended never hurt him, yet how would any of that help them now? It was just data: another series of facts and details his inner spermologer couldn't resist. He looked over at Will and his chest ache with every laboured breath his brother drew. If they could just get outside… They were still in London; he was sure of it.

Seven years spent sharing a room with William Morstan Watson-Holmes had to teach you something, he reasoned.

And, suddenly, he knew what he had to do.

His frozen toes searched the cement around him, landing on a chunk of gravel and skittering it across the floor. At once, Will's dark eyes flashed up at him, damp with tears and wretched. Hamish held his gaze for a long moment before cocking his eyebrow in a perfect imitation of their father. The corners of Will's lips twitched in reply and he nodded.

Seven years spent sharing a room had taught him something. Seven years of surviving Christmas with an ill-tempered Mycroft, matinees with their grandparents, their father's moods, illicit hide-and-seek in Scotland Yard, all of it had taught him well the lesson all children learn when living solely in the adult world: they didn't need words to conspire.

From what Hamish could see on his brother's sooty face, Will remembered this lesson, too.

Hamish shifted back against his pole. You okay?

Will's legs stretched on the damp floor. I'm scared, Mish.

He took a breath and looked back at his brother. Me too.

Will swallowed and shook his head. Do you have a plan?

Hamish coughed wetly. Almost. He coughed again. Yes.

Will sat up a little straighter. His shoulder rolled against the metal of his pole. His wheezing was getting worse, but his gaze had never been steadier. Excellent. He took a breath.

'Hey, mister?' The man in the hat was silent. 'Oy! I know you're over there!'

A metal chair shifted beneath his weight. 'What do you want?'

'I need to do a wee.'

The man in the hat cleared his throat and spat. 'Piss yourself. I don't care.'

Will's face fell, his eyes desperate. 'Please don't make me say it…'

'Say what?' Will didn't reply. 'The fuck you on about?' He blushed, his eyes lowering to the ground as he muttered. 'What?' the man called.

Will's flush deepened. He addressed his lap. 'I have to do a poo, too.' Hamish stifled a giggle. Will glared at him.

'Jesus Christ…' The sound of metal scraping on cement and heavy footsteps made their way over.

Hamish stuck his tongue out at Will. So far so good.

Will crinkled his nose and glared. We're not out of the woods yet.

'Knock it off!' The man in the hat came up behind Will and fussed with the ropes on his pole. Hamish coughed against the heavy stink of menthol, sweat, and cheap whiskey. The man cleared his throat and spat again. Flecks of spittle stung Will's cheek. 'Come on, you,' the man said, hefting him to his feet.

'Where are you going?' Hamish cried.

'Shut up!'

'You can't just leave me here!'

'I said shut it!'

'Please!' he screamed. The man's hand barrelled toward his face. Hamish winced, but the blow never came. The man balled his fist and shoved his hand in his pocket as Hamish wailed. Hamish caught Will's eyes.

Interesting, they said.

'Please don't leave me here! I'm scared!' His voice crept higher and higher, ear-piercing in the empty building. 'I won't run away, I promise! Please!'

'Fuckin' hell…' He grabbed at the ropes around Hamish's pole, awkwardly holding Will against his side. He yanked Hamish up with one hand. 'Now keep quiet! Or I'll tan both your hides.'

His brother caught his eye again and smirked, and Hamish felt a rush of warm relief surge up from the cold concrete. Will was back. Trouble was brewing in his blue-grey eyes.

They might wake up from this after all.