‘We’ll have to get you inside the household somehow. A servant or summat. John Leadingham’s looking into it.’

‘I can’t be a servant!’ Luke said, horrified.

‘What! Too proud to sweep a floor?’

‘No! I don’t mean that. I mean, I wouldn’t know how! How could I be a footman in some great house? I wouldn’t know the first thing about what to do – I’d get the sack before my feet had touched the ground.’

‘A footman no, but there might be something else. You’re too old for a boot-boy, but a garden hand maybe. I don’t know about London, but John says they’ve got a great rambling place in the country with a hundred acres and more. There must be work for a man there.’

‘What if they’re not in the country? Don’t the gentry come up to town in the autumn?’

‘I don’t know.’ William shook his head. ‘You’re asking the wrong bloke, Luke. But where there’s a will, there’s a way. If there’s a chink in their armour, John Leadingham’s the man to find it. By fair means or foul, we’ll get you into that house. And after that . . .’

After that, it would be up to Luke.

‘I’ve got a plan.’ John Leadingham tapped the side of his nose as they walked down the narrow alleys, tall warehouses towering either side of them, their top storeys disappearing into the shrouding murk. Luke could hear the lap of the Thames on the mudflats and the bellow of a horn as a ship made its way downriver in the thick yellow fog.

‘What is it?’ Luke asked, but John shook his head.

‘Ask me no questions, young Luke. You’ll know soon enough, but for the moment I’m still working out some of the finer details. Now . . .’ He stopped at one of the furthest warehouses – a tumbledown wooden structure that looked as if it might just slide into the Thames mud at any moment – and drew a key from his pocket. ‘You’re not squeamish of a little blood, are you?’

‘No,’ Luke said, but his stomach twisted, wondering what awaited him inside the warehouse. He thought of the nights when William came home with blood on his hands and shook his head, pale-faced, when Luke asked him questions about what he’d done. Would it be a witch, captive, awaiting trial?

The door swung wide and the stench of blood that flooded out made him take an involuntary step back, but John Leadingham strode inside as if he hadn’t noticed.

Luke found himself standing tense, his muscles ready to fight or fly, as the gas-lights flared out across the warehouse. But then he laughed, the noise sounding strange and light with relief in his own ears.

‘Pigs!’

Carcasses swung from hooks in the beams and there were bones stacked by the door out to the wharf. And not just pigs, he saw. There were sides of beef over the far side, and sheep too, stripped of their wool and skinned, with sharp grinning teeth and staring, round eyes.

‘Well, what else did you expect? I’m a butcher, ain’t I?’ John swung the door shut with a dull thud of rotten wood and took off his coat. ‘It’s an abattoir.’

‘Why’ve you brought me here?’

‘Because I’m not sending a sheep to the slaughter – pardon the pun.’ He pulled on a bloodstained apron and picked up a knife. ‘You can fight, Luke, I’ve seen it. Even better if you’ve got a bit of beer in you. But you can’t kill. That’s a different skill completely – and one you need to learn, and fast. I’m not saying you should gut this girl like a stuck pig, of course not. I’m hoping you’ll get the job done a good deal more subtly than that. But the fact is, you may find yourself in a tight corner, and carrying a knife and knowing where to stick it can take you a long way.’

He threw an apron at Luke and then a knife, hilt first. Luke fumbled the catch and cut himself across the palm, and John Leadingham grinned.

‘Lesson one – make sure you end up on the right end. Now . . .’ He pointed at the corpse of a pig, swinging gently on a butcher’s hook driven in under its chin. ‘This is a man. Where are you going to stick that thing?’

For the next three hours Luke worked harder than he’d done in a long time, and by the time Leadingham let him stop he was sweating, gasping and spattered with gore, the knife slipping in his bloodstained hand.

His head was spinning with all the new information – where to nick an artery, where to slice a tendon. What would incapacitate a witch, and what would merely slow him or her down while they healed themselves. And all the time, as John Leadingham barked out, ‘Femoral artery, kidney, achilles,’ Luke stabbed the pig and yanked out the knife.

‘Don’t think strength can help you. If they clock what you are – carotid artery – your best bet is to get their trust, get in close, then when they least expect it, strike. Spleen! Stick ’em as hard and fast as you can, and get out. Pulmonary artery! No, not there, you dolt. That won’t do more than give them a nasty scar and they’ll be up and at you before you can say “Spring-Heeled Jack”. Here . . .’ He stabbed the knife in between the ribs with a grunt and a crunch that made Luke’s stomach turn. ‘You’ve got to remember, a witch’s magic lies in their strength, and their strength lies in their blood. Draw off enough blood and you’ll weaken their magic too. Right kidney! Good, good man. Now, go for the tendons behind the knee – no, don’t stab, slice. That’s right. Brace their weight against yourself to get a purchase – and remember they’ll likely be slippery with blood.’

At last he stopped and took Luke’s shoulder, turning him panting and red-faced to look at him.

‘This is easy enough with a dead pig that doesn’t dodge or strike back or cry with pain. Now I want you to do the same thing, but imagine this pig is a girl – a girl who cries out as you come at her with the knife and tries to get away.’

‘You want me to imagine this pig is a girl?’ In spite of himself, Luke stifled a smile. His chest was rising and falling, and his limbs felt like glue, but the idea still made him want to laugh. ‘How desperate d’you think I am?’

‘Just try it.’

‘If you say so.’ It was hard to think of anything but the fat, bristly carcass swinging to and fro, but Luke shut his eyes and pictured a girl hanging where the pig was, a blonde maybe like Phoebe, her blue eyes wide with horror as he came towards her with the knife. ‘All right, I’m picturing it.’

‘All right then. Go. Aorta!’

Luke opened his eyes and lunged, knife outstretched, for the pig’s throat – and behind him a voice screamed, ‘No! Oh God, spare me!’

Luke stumbled, slipping in the blood, and the knife fell from his hand as he slammed against the pig, grabbing at its cold, clammy flanks to try to steady himself.

‘What the hell?’

John took a step forward out of the shadows and his face was grim.

‘That was all it took, was it? Me screaming like a girl – and a bloody poor imitation, if I do say so myself – and you were tripping over your own feet and turning to jelly?’

‘Damn.‘ Luke could have kicked himself. Damn.

‘You think you’re a man, Luke, and you are – but it’ll take more than a man to kill this girl. It’ll take a Brother. One of the Malleus. The test of the knife, the test of fire – they’re nothing to this. Because with this you have to defeat yourself, as well as the witch, d’you understand? They’ll use every weapon they can against you – they’ll weep, they’ll plead, just as they’ll fight and lame and maim. If you’re afraid—’

‘I’m not afraid,’ Luke broke in roughly. John put his hand on his shoulder.

‘I didn’t say you were, son. But if you are afraid, they’ll see that and they’ll turn your fear against you. And if you have a kind heart, they’ll turn that against you too. So you must have no heart, understood? You must have no fear. You must be nothing but the hammer.’

4

‘There’s worse fates than marrying for money, Rose.’ Clemency put a sugared plum in her mouth and smiled, her plump cheeks dimpling, her lips sticky with syrup. ‘I should know. And better a rich wife than a poor spinster.’

Rosa sighed. Clemency put it gently, but the truth beneath her words was hard. What other fate was there for a girl of her class and education? She had no way of earning a living, she knew nothing. And what was the alternative? Living out her days as Alexis’ unwanted spinster sister – despised by everyone and dependent on Alexis for everything from dress money right down to her food.

‘But . . .’ She bit her lip. She wanted to say: But it’s different for you. But was it? She looked at the portrait of Clemency’s father-in-law, Lionel Catesby, which hung between the two tall windows overlooking the park. The long golden beard, the red nose, the great belly like an aged Henry VIII. Philip was not his father – not yet. But he was halfway there and in a few years . . . Rosa looked at Clemency and tried to imagine Philip Catesby knocking on her door, climbing into her bed, kissing her with that great scratchy blond moustache and putting out a hand . . .

Heat rose up in her face and she fumbled and dropped her teacup.

‘Oh, Clem!’ She jumped up, dismayed, as the tea flooded out across the Turkey rug, soaking into the silk. ‘I’m such a fool! Oh, where’s my wretched handkerchief?’

‘Don’t be silly. Sit down, Rose, and stop flapping.’ Clemency stretched out a hand to the bell and a moment later a maid came hurrying in.

‘My cousin has spilt her tea,’ Clemency said. ‘Would you clear it up and refill the pot, please, Liza?’

‘Yes, ma’am.’ Liza curtseyed and then knelt, her hand outstretched over the stain as she whispered the words of a spell. Rosa watched, relief fighting with envy as the tea stain misted into the air and disappeared, leaving the rug clean and untouched. If you married Sebastian, you could have a maid like Liza, her treacherous subconscious whispered. No more hiding and whispering and pretending to be what you’re not. If you married Sebastian . . .