Thomas True sat upon the roof of the postal coach as it trundled over divots and bumps, descending the North Road to London. Piles of boxes and trunks bounced beside him, straining their lashings as the wheels screeched against the ancient track. The hills were behind them now, so too the dappled groves and leafy thickets, for the countryside was growing sparse and thin, devoured by the rapacious city.

The coach turned a gentle corner then mounted a bridge spanning a brook – and there was London rolling up on the horizon, grim and grand, the freshly budded dome of St Paul’s Cathedral gleaming amidst a morass of timber and brick. Far below, the distant spires rang with happy bells, calling God’s children to prayer.

My new home, thought Thomas as they descended the cleft of the valley. My new life.

He watched in wonder, hardly noticing as the fields folded in around them and the crops blackened. A chill was growing through him despite the sweltering weather, and he wondered whether he shouldn’t turn back.

‘Driver,’ he said with a gulp, ‘perhaps I might climb down and make my way home?’

His request was cowardly, he knew as much, yet if the coachman heard his feeble voice above the din of the ungreased axles, he gave no sign of it and whipped the horses on.

Thomas had made the decision to escape his father’s rectory the night before, yet now he saw the danger of it: after a lifetime of imprisonment, might he find himself lost and lonely amongst so many people?

Surely there was no need to worry about that: his cousin Abigail was waiting for him in the candle shop on the bridge, and besides, London had to be friendly, or why should so many people choose to live there?

He held on to his hat and gripped his trunk as they dropped down a steep slope into a tunnel of trees.

‘Are we nearly there?’ he called to the coachman, ducking under a low-hanging branch as they burst back into the sunshine. Thomas let out a startled cry, for the magnificent city had grown three times the size. ‘By the saints!’ he laughed. ‘Will you look at that?’

Glory, oh blessed glory to be away from home. Farewell Highgate with its grey rectory and its gloomy little taverns and paltry expectations. Goodbye sermons and sins, goodbye graveyard, goodbye dry food, farewell pretence and piety, good riddance to misery, tearfulness, and waiting. No more waiting for Thomas True, only beginning!

He was overcome with excitement, his every nerve tingling as the horses charged towards the City gates.

Ever since boyhood, he had dreamed of this. For how many hours had he stood on tiptoes with his nose on the sill of his attic window, peering down at the sinful stew? Countless thousands of hours, every day and every night for all his twenty years. Unable to contain himself, he twisted with a triumphant cheer and waved goodbye to the receding countryside.

He turned back and hunched his shoulders, realising the buildings were almost upon him, and he had a premonition that the second he passed through those gates he would somehow cease to be Thomas True at all – which perhaps was the point of his journey. Yet while he relished – yes he really did relish the thought of disappearing amongst so many strangers – he hardly fancied being a stranger to himself. At least he would have his smart new clothes to wear. He looked over his shoulder and gave a squeak.

‘Driver,’ he said, pulling on the horse’s reins. ‘You must take me back; I have forgotten my trunk!’

The coachman ignored him, and soon the wheels were grinding across cobbles, the unbearable noise blending with a gathering roar so furious that Thomas thought he heard his father amidst the din. He shut his eyes and covered his ears.

Instantly, he was a boy again. Cowering beneath a Bible to the incantation of a sermon. He was a foul sinner, a devil child, a demon fit for nothing but flame. His ribs contracted to the memory of a snapping belt, and with tears in his eyes he was hiding in a burrow dug into the side of a graveyard wall…

There came an almighty bang, jarring Thomas’s bones, and when he opened his eyes he found himself surrounded by tottering homes six storeys high, and everywhere so many people of all shapes and sizes, with every style of gown and wig, a din of jostling men in tall hats, broad hats, tricorn hats, buckled frock coats and silver-topped canes, rubbing shoulders with sailors, lobstermen, cockle sellers and thieves. It was a wonder any of them could hear amidst the din, for there wasn’t a moment of peace, and oh! Thomas clapped his hands across his mouth and nose. The rivers of piss that flowed down the dusty kennels and rose up in clouds of steam. He couldn’t breathe.

At last, the driver was forced to steady the coach behind a clot of tumbrils and chairs. He gave his horse an impatient flick of the reins before looking over at his passenger with a dry chuckle. ‘You’ll grow used to the stench, young sir,’ he said. ‘Just have to take it in a few times, see?’ He pursed his lips and sucked a deep breath as though smoking a hookah pipe. He turned a nasty shade of green until his fourth gulp, when he smacked his lips and shook his jowls, hearty as a king.

Thomas frowned at him, holding his breath with his cheeks puffed out. He could feel the acrid air pressing its fingers up his nose. He could not do it, he would have to choke, yet just as his vision went blurry the coach bounced over a loose cobblestone and tipped him to the ground with a hard thump, rolling across the road like a baker’s pin.

‘Wait!’ he coughed, climbing to his feet, yet before he could push his way through the crowd, he was lost amidst the tumultuous racket of the packed street. ‘Come back!’ he said, turning in circles, clasping his face. ‘Oh my saints, what shall I do? What shall I do?’ He searched his coat pocket and found his purse with all his money, wiping his brow with relief as he looked about.

He bit his lip, tracing his eyes across the high stones of a building by his shoulder. It was very large indeed, with blank slits for windows. A prison, surely, and a forbidding one at that, while on the other side of the street the houses and inns were busy with so many hoardings and swinging signs he could hardly see the bricks behind them. He stopped still, catching sight of some movement at the rooftops, and craned his neck. He could hear a bell tolling, faint and ethereal. At first, he took what he saw for birds, then for black cats, yet they couldn’t be, for they moved with skinny limbs and jutting knees. It was a gang of twenty soot-black children, he was sure of it, skittering over the brickwork below the eaves. He shielded his eyes for a better look, yet he found himself blinded by the sun.

‘By your leave, sir!’ came a bellowing voice as a pair of charging chairmen hurtled by, and with a yelp, Thomas tripped over his heels and fell face first into a narrow alleyway.

‘For the sake of angels,’ he said, brushing himself down. ‘What a clumsy oaf you are.’

‘Clumsy but handsome, I’d say.’

Thomas rolled over to see a young, attractive man leaning against the bricks. He was slender with a long nose, freckles all over his face and a twisted periwig. He had his foot cocked against the bricks, and he was smoking a pipe.

‘Good day to you,’ said Thomas. ‘Is this your alleyway?’

The man raised his pale eyebrows, looking around. ‘It’s anybody’s if they want it.’

‘Ah,’ said Thomas, nodding sagely, for London seemed to suit such things. ‘I only arrived a few minutes ago and I’m already lost. I said to myself this morning: “Now Thomas, don’t get lost and don’t forget your trunk,” and what did I do? I forgot my trunk, and here I am lost.’ He looked at the man with a hopeful smile. ‘Where am I exactly? It hardly matters; I’m lost no matter where I am, even in my own brain, and I forget to remember things, no matter how hard I try, and doesn’t it annoy my mother and father, who don’t even know I’ve left, and well, if they had known my plan to run away I don’t doubt for a second… ’ He caught sight of the man’s eyes glazing over and gave a nervous laugh. ‘Forgive me, I do prattle; it’s only that I feel sometimes, or rather I do wonder sometimes… ’ He shrugged. ‘What use I am to anybody?’

The man pulled his pipe from his lips, revealing a jumble of wonky teeth. ‘Funny, I was just thinking the same thing.’ He folded his arms, the muscles stretching the faded sleeves of his patched coat. ‘Where you supposed to be then, if not by Newgate?’

‘Is that where we are? Newgate? Saints, that can’t be near the bridge. I was on my way there when the coach took a swerve and tossed me into this alleyway… ’ Thomas fiddled with his coat buttons ‘…with you.’

‘Right you are,’ said the man with a quick smile. He flicked his eyes over...