For a minute he thought of dropping the knife, of running – but there was his uncle. And more: at his back there were the shadows of his mother and father and all they’d suffered. If he couldn’t do this thing for his own honour, surely he could do it for theirs?

Remember why you want to join, the voice in his head hissed, full of venom. Remember what it’s all for. Do it, you coward.

He lifted the knife and stabbed it into his gut, gasping as the hilt hit hard against the skin of his belly and he could go no further.

For a minute he felt nothing, but then pain blossomed across his side and the blood began to trickle down his belly, soaking into the worn cloth of his work trousers. He felt sick, sick with pain, sick with the knowledge of what he’d done.

‘Take it out,’ said the man, his voice hard and clipped. Luke closed his eyes, dreading the slick, grating tug and the mortal gush of blood and guts. Then he pulled.

There was a murmur around the circle, an exhalation of breath and then a few relieved guffaws.

Luke opened his eyes and looked at the knife in his hand.

For a minute he didn’t understand. His eyes were blurred with sweat and he had to lift his arm to wipe his brow and clear his vision. Then he saw.

The blade of the knife had slid up inside the hilt, until only a sliver remained – just an inch, barely. It was that which had stabbed his side, making the blood come. But it was not a mortal wound, nothing like it.

‘Well done, Luke Lexton,’ said the man, his voice warm and strong. He held out his palm and Luke gave back the knife with a hand that shook. ‘Well done. You were strong and steadfast, and your courage saved your life. Look,’ and he showed Luke the little button in the handle which, if the hilt were gripped hard and firm, released the blade to slide inside the hilt.

‘If you’d not held fast, if your grip had wavered, it would’ve been death to you. D’you see? The switch wouldn’t have released the blade, it would’ve stayed firm and stabbed you to death. Only someone who grips the hilt and drives the knife firmly home can live. It’s a test of trust and faith. To show that although what we ask of you may not always make sense, there’s always good reason behind it, and only that trust will see us all through.’

Luke closed his eyes, feeling the blood hot on his side and the weakness in his legs, and he nodded, wishing it were all over, wishing he could go home, but knowing it had barely begun.

‘You’ve passed the trial by knife. The second trial is the trial by fire,’ said the man. He stepped forward, towards the fire, and Luke saw that there was something resting on the edge of the grate: a long metal handle, with the far end plunged into the heart of the coals.

The man wrapped a cloth around his hand, picked up the handle resting on the hearth and drew the glowing tip out of the fire. It was a brand: he’d seen one often enough to recognize it. Luke’s uncle used them on horses and sometimes cattle, if their owners needed them to be marked. He’d even branded a few animals himself, when his uncle was busy, and he’d always winced at their pain and their bellowing cries, but never thought that one day . . .

The end glowed so bright he could not see the design, only the heat that shimmered from it, making the air ripple and waver. Then the man thrust it back into the heart of the fire and spoke.

‘Take off your shirt.’

Luke swallowed against the dryness in his throat and he began to fumble with the buttons of his shirt. The men watched, their eyes glinting in the firelight as his reluctant fingers loosened one button, then two, then another, and another, until his shirt hung loose and he could feel the heat of the fire on his naked chest and belly. Blood was already crusting around the cut he’d made, the trail down his side turning black and cracked. He took off the shirt and laid it on the floor at his feet.

‘This test is a test of endurance and silence. You must not flinch. You must not cry out. By enduring this test in silence you show that your loyalty to the Brotherhood may be tested, but you will not betray them by any cry or word. Do you understand?’

Luke nodded, not sure that his voice would obey him, but the man shook his head.

‘Speak, Luke. Do you understand?’

‘I understand,’ he said hoarsely.

‘Then kneel and hold fast to the chair.’

Luke knelt, holding on to the back of the chair, feeling his breath coming fast and his heart racing beneath his ribs as if he might be sick. One of the other men held on to the seat of the chair so that it wouldn’t rock or fall if he flinched or fell himself. Luke heard the whisper of ash as the man took the brand from the fire, and his blood sang in his ears, a strange, fierce, fearful song.

‘Hold fast, Luke Lexton,’ said the voice.

Then there was a hiss and a heat against his shoulder. For a moment there was no pain and he thought it was all a trick, as the knife had been. But then a roaring, tearing anguish began to engulf his skin and his muscles, until it seemed as if even the bones of his shoulder itself were burning. A great bellow of agony rose up from his guts and he almost cried out, but just in time he remembered his promise of silence and he gripped on to the struts of the chair and bit into his own forearm so that no sound escaped but his tearing, whimpering, ragged breaths.

Beneath his closed lids, constellations of pain exploded and spun and his blood roared in his ears. He wanted nothing more than to beg for it to stop, to scream for water, for pity, for anything.

The circle of masks was completely silent, listening to his struggle, listening for any cry. Then, after what seemed an age, the first man spoke.

‘Well done, Luke Lexton. You’ve passed the trial by fire.’

There was a hiss of breaths released around the room and Luke gave a sobbing groan.

‘Get something for the burn,’ the man said, and one of the masked men came hurrying forward with a pot of grease, like the one Luke’s uncle used when he burnt himself at the forge. He felt his shoulder smeared with the ointment and then hands helped him to sit, pulling him to a settle, dressing the burn with a clean cloth.

‘You’ll have a wound for a few days,’ said the man. ‘And then a mark, as we all do. As best we know, the meaning of this mark is not known to any outsiders. We show it to none but our wives – and they mustn’t know what it signifies. D’you understand?’

This time Luke could not speak, he only nodded, and the man seemed satisfied.

‘Good. Good man, Luke Lexton.’

They passed him his shirt and, with their help, he struggled into it, feeling the bandage over his shoulder grate and move as the rough cloth jostled the dressing. There were teeth marks in his arm. He’d not broken the skin, but there would be a welt there for a while.

Someone passed him a half-drunk tankard and he drained it, before he realized that it was not beer, but gin. It burnt his gullet and then smouldered in his gut, and he half sat, half lay across the settle in front of the fire, feeling the sick cold in his limbs subside a little with the warmth of the fire and the warmth of the gin.

‘And now, for the last trial – the trial of the hammer.’

‘Wait,’ said a voice from beneath a hood, and for the first time Luke recognized his uncle’s voice. ‘Give him a minute, Brother. He’s in no fit state—’

‘He’s conscious,’ said the man in the gown sternly. ‘He knows his own mind and can plead his own case. Luke Lexton, are you fit to continue?’

Coward, whispered the voice.

Luke was sick and sweating, but he managed to sit up straighter. He wasn’t about to back down now and shame himself and his uncle and the memory of his parents. He nodded.

‘I can carry on.’ His voice was strange in his own ears. His throat felt tender and raw, as if he had screamed himself hoarse, though he knew full well he’d not made a sound except for shameful pup-like whimpers. He wondered if his uncle had been this weak, or if he’d borne the brand in proud silence, and he gritted his teeth and forced himself fully upright. ‘I can carry on.’

‘Good man,’ said the man in the gown. ‘Now, this last trial is different. All we require of you tonight is that you accept the task and undertake to do it to the best of your abilities, or die in the attempt. Tonight the moon is full – when the full moon rises again, either they must be dead, or you. D’you understand?’

‘Yes,’ said Luke, though he did not.

‘Bring out the book,’ said the man. There was a rustle at the back of the room and an old masked man limped slowly forward, a huge brass-bound book in his hands. The man in the gown fitted a brass key to the lock and opened the book.

Inside was page after page after page of closely written names, some with a line through, some scratched out so harshly that the paper was rough and hollow.

‘This book contains the name of every witch known to this organization – some of them listed thanks to you, Luke – and every one we’ve sworn to hunt down and kill. The men and women named here have poisoned our brothers and sisters, enslaved them, enchanted them, even killed them. Every one has a heart as black as pitch and it is our sworn duty not to rest until London is wiped clean of their kind. After the trial of the knife and the trial by fire, we ask our Brothers for one more trial to prove their worth – the trial of the hammer: they must pick a name from the book and kill that witch. Do you understand?’

‘Yes,’ said Luke. And now he did. He stared at the list of names, the faded, scratched handwriting swimming before his eyes. ‘What of the ones who’re scratched out?’ he asked.