Whatever Jack privately thought about their chances, he didn't betray any misgivings. He swung the axe, his tread was bouncy – for all the world as if he was looking forward to the fight.

He was, at least, very used to planning things that could end his life without displaying a flicker of emotion – though, every so often, Ellini caught him glancing at her, as if he was wishing she wasn't there.

She knew that feeling. She could see this going very badly, but every time she saw it going badly with regard to Jack, she came up against a brick wall in her thinking, and couldn't go any further. She was willing to risk everything for Danvers until she came to this point. And then she didn't know what she would do.

As they walked – because Jack could never bear to be idle – he started to work on Inspector Hastings. It was like the dazzling diplomacy of his India days, only there was more anxiety behind it now. He had the same energy, but it was nervous and brittle, and she saw how easily it could turn into despair.

"Of course you don't want to kill her, Sammy, and it does you credit. But you don't know what she is."

"Everyone keeps saying that and then refusing to go any further!" the Inspector snapped. "What is she then, if she's too advanced for me to comprehend? Why don't you dumb it down a bit?"

"Well, she's a murderess, for starters. Remember Professor Carver at the Chemistry Faculty? You think I didn't make enquiries about him? Found decapitated inside her cottage. She put his head on her shelf alongside her extensive collection of severed genitalia."

"That doesn't prove anything," said the Inspector, waving a hand to ward off the unpleasant image. "And even if it did, it would need to be dealt with by a judge and jury, not a man wielding a sixteenth-century rapier!"

"She's kidnapped Danvers," Jack put in, as if he'd been lining up the next argument while the Inspector had been talking.

"Yes. And I intend to arrest her for it."

"And what then? There's no cell that could hold her – there's no court that could judge her!"

"That doesn't mean we just butcher her without asking questions!"

"What questions do you think we can ask?" Jack's voice was getting shrill now. "'Why did you do this?' 'Please will you refrain from doing it to me?'"

He stopped, because Broad Street had come into view, deserted except for the figure – it was two people, but one figure – standing in the middle of the road.

The martyrs had been burned in Broad Street, though their memorial was around the corner in St Giles's. Nothing marked the exact spot except a pale stone set into the flagstones of the street, carved with a cross.

Danvers stood on top of it, very stiff and straight, with his hands bound in front of him. Myrrha could just be seen over his shoulder – she wasn't taller than him, but somehow she had elongated herself for this moment, because she glowered out from over his shoulder like a second head. Ellini supposed she was thinking too much about the martyrs, because she couldn't help imagining that he was tied to a Myrrha-shaped stake.

And just as Myrrha couldn't naturally have been that tall, she couldn't really have been that uninjured. Her skin wasn't the charred black of the arm that had come out of the mirror. It was pale and sleek, only occasionally mottled with darker patches – and even those looked like smudges of soot rather than severe burns.

She was using some portion of her magic to present a decent appearance, then. Ellini could scarcely believe she still cared about that, but it could be useful.

Still, Myrrha couldn't change the burning scent that rose off her, with all the stomach-churning wrongness of scorched flesh. Elsie's hand tightened on Ellini's as she smelled it.

Danvers was bound with thin, glowing ropes that looked like the electric filaments at the centre of a lightbulb. Ellini could see a shimmer of heat in the air around them. They had scorched through his jacket, but they were sparing his flesh, for the time being. Perhaps Myrrha could control how deeply they bit into him.

Looking up, Ellini saw that an opening had been torn in the overhanging thatch of green vines. Myrrha had already carved out her escape route. All she needed now was the knife, and she would have Robin back, and nothing would be able to drag her to the city of Oxford ever again. She could plan Elsie's death at leisure. Elsie's death could happen anywhere.

The chance was slipping away from them – the chance that they'd never have again. If only they'd had more time to plan – if only Robin had let her in on his mad scheme of self-destruction.

Well, what then? she thought. You'd have tried to stop him. Or you'd have given the game away. Robin knew his chances weren't good. He will not be at all surprised to find himself resurrected, and Myrrha's slave again.

But he always backs the winner. And for some reason he thought that would be you.

They stopped when they were about ten feet from Myrrha – the stench of burning flesh wasn't easy to bear – and Inspector Hastings raised his revolver.

"I'm arresting you in the name of Her Majesty, on charges of kidnapping, suspected murder, and conspiracy to cause a–"

Myrrha burst out laughing before he could even finish. "Oh, come on. Is that supposed to mean something to me? Besides, I haven't conspired to do any of this. I am improvising, to great effect."

Inspector Hastings started to argue, but she waved a hand and seemed to sweep his voice away, leaving him mouthing uselessly, growing redder and redder in the face.

She pouted at the rest of them, leaned her cheek against Danvers's temple, and made sure they all saw him shudder. For Elsie's benefit, she added, "He's here, little sister. Quite unharmed. Say hello to her, Danvers, she's having kittens about you."

Danvers didn't speak. He went on breathing heavily through his nose, his lips clamped shut and his chin turned upwards. The picture of English stoicism.

Something blurred on the edge of Ellini's vision, and she turned her head in time to catch the tail-end of Jack's signal.

A whip-crack of gunfire echoed around Broad Street. Rifle-smoke was rising from the clock-tower of Trinity College – Jack's snipers, presumably, the ones who hadn't run away. Ellini couldn't tell whether they'd hit Myrrha – perhaps they'd been aiming to miss, because they couldn't be sure of not hitting Danvers at that range. But they were enough to make her turn her head, and that was all Jack had been waiting for.

He stepped forwards and swung the axe – aiming, as far as she could see, for the narrow space between Myrrha and Danvers, as if he meant to prise them apart that way. But Myrrha's hand shot out, quick as a snake, and caught the axe by its handle before it struck

For just a moment, the hand that caught the axe was blackened, glinting with white bone just under the surface, but then she was under control again.

One of her orange filaments shot out and caught Jack around the neck, dripping sparks, lifting him just clear of the cobbles, so that the toes of his shoes trailed along the ground. He didn't let go of the axe. The filaments were choking too tight for him to cry out in pain, but he didn't let go of the axe.

Ellini raised her voice, gathered the ragged dregs of her magic, but Myrrha staggered forwards before she could do anything, her mouth twisted in pain. When she opened her lips to take a breath, her tongue was red with blood. She twisted round, lowering Jack to the floor, but not releasing the orange rope at his throat. Inspector Hastings had crept round behind her and driven the point of that rapier into her back.

For half a second, Ellini hoped. There were spots of blood on Myrrha's lips now – they seemed to form spontaneously, like dew. She hawked them back and spat them onto the ground.

But the blow was too tentative – Sam hadn't driven the point deep enough, probably for fear of hitting Danvers. And he was still holding the tangled hilt, shaking, with none of the old, iron-hard certainty in his face.

Ellini should have seen it when he had first raised the revolver to threaten her. He didn't believe what he was doing. He believed the words of the arrest – he believed she had caused a breach of the peace – but the threat behind it was empty. He couldn't bring himself to kill her.

Myrrha reached back and drew out the blade with a wet, smacking sound. Drops of blood showered the cobbles behind her, but she didn't stagger again. With a disdainful flick of her arm, she hurled the sword – and Sam with it – to the other side of the street. They clattered to a halt outside the gates of Trinity, and then they were very still. Ellini couldn't tell if he was still breathing. All the air in the intervening space was blurred with heat.

Myrrha leaned down to Jack – still on his knees, with the orange filament fastened round his throat – and said, "You could only muster up one of the guardians of Oxford, and his heart wasn't even in it. My Robin died to give you this chance. It's pathetic to see the way you squander it."

She clenched her fist, and the filament tightened round his throat. Ellini reacted instinctively. It wasn't even a spell, just a sudden surge of emotion. She narrowed her eyes and clenched her fists and felt the fire crackle furiously in her hair.

She focused on the heat in the filaments around Jack's throat – felt it flaring and dipping in time with her own temper. She tried to cool it and control it, tried to coax its heat away to kindle in Myrrha's shift. But there was barely a flicker – barely a wisp of smoke – before Myrrha looked directly at her, her teeth clenched behind her lips.

"Oh, you think you still own the fire, do you? You suffered in it for years, I'll give you that, but did it burn you? Did it fuse itself to your skin and shoot along every one of your nerves? Did it take away the only man you've ever loved? Mastery of the fire comes through suffering, and for all your masochistic tendencies, you haven't felt an atom of my pain. I can show you, if you like."

She raised a hand and slowly curled her fingers inwards, one by one, as if enacting a very lazy countdown.

There was nothing to burn in the street between them, but still, a wall of flames reared up and moved towards Ellini, pushing heat in dry, sickening waves before it. Ellini backed up a few paces, until she felt the stones of Exeter College pressing into her shoulder blades.

She raised her hands and set her teeth and tried to push the flames backwards, tried to draw away their heat and their ferocity, but they were so hungry. They hated her so much. They were snapping and snarling at her, like a dog straining at the end of its chain.

The skin of her palms was blistering, her eyes were streaming, her throat was seizing up with smoke. And she knew, the moment she dropped her hands, that it would consume her.

She could only see the figures of her loved ones as shadows through the wall of fire. She could see Danvers, still as a man tied to a stake, and Jack, on his knees, struggling against the filament wrapped around his throat.

He was using the axe to try and prise his restraints away – and maybe there was a sputtering, a wisp of damp smoke rising up from the filaments where the axe's blade touched them. But he wouldn't be in time. There was no time left. She could smell the scorching of her own flesh.

Elsie's voice came through the roar of the flames as a girlish squeal. "That's enough! Stop it!"

The flames died down as suddenly as they had reared up. There was no hissing, no quenching, no steam or ash – they just evaporated, leaving cold air to rush in in their place and strike Ellini across her sodden cheeks.

She collapsed, nursing her hands, and then felt someone hurry to her side, haul her up, press his lips to her sweat-streaked forehead. Jack had managed to get free somehow. She hoped it wasn't at the cost of any of his limbs. Her eyes were still streaming, and it was hard to get him into focus.

"You mentioned a civilized exchange," Elsie prompted.

Ellini blinked the sweat out of her eyes, and Myrrha swam into focus, one hand pressed innocently to her chest. "Of course, my dear sister, I would be only too happy to oblige you. These morons wouldn't believe how powerless they were until I showed them, but I knew you would see sense."

"What do you want?"

"Well, the knife, obviously."

"You can have it," said Elsie.

"And her arm." She curled out a hand lazily, pointed in Ellini's direction. "Her right arm. Cut off at the elbow. In front of me. No anaesthetic. I want to wave goodbye to her with it before I go."

Elsie couldn't see where she was pointing, but she obviously caught her drift. There was a moment of silence, and then Myrrha went on, as if she could see the need to press her case.

"She'll survive the amputation, I daresay. She has magic. And you'll note, I'm not asking for her life – I'm not asking you to deliver her into my hands so that I can cut bits off the bitch at my leisure. I'd say I'm being very restrained, when you consider what she took from me. What's a little arm – half a limb – compared with a man's life? I will kill Danvers if you don't give me what I want. And he is emphatically – tediously – human. There'll be no resurrection for him."

Elsie turned her face to Mr Danvers – started towards him as if she couldn't contain herself anymore. "What do I do? Mr Danvers, what do I do?"

Danvers answered her without opening his lips very wide, but his voice was still steady. "Let her kill me."

She stood very still for a moment. And then she shook her head – more as if she was trying to dislodge something than defy him. She took half a step towards Ellini. "You have to–"

"Oh, you're kidding me," said Jack, his voice still raw from the filament. Ellini could see scorch-marks at his throat.

"It's one limb in exchange for a man's whole life!" Elsie protested.

"Look, I've put up with a lot from you, I really have–"

Ellini shook her head to hush him. He was still rational enough to heed her, but he wouldn't be for long.

"Elsie, I would give my right arm to save him – I would. But this isn't saving him. She wants my arm so she can make the bone into a weapon to kill you. And you know that when she tries to kill you, he'll be standing in front of you. This is just delaying the inevitable."

"It buys us some time at least!" said Elsie. "We can think of another way–"

"There is no other way."

Elsie shook her head again – with that curious, rapid, dislodging motion, as if she wanted to shake the flies away. "You're just scared of the pain – and of being disfigured–"

"I've had enough of this," said Jack, stepping towards her with the axe raised. "There is no way in hell, do you understand me?"

Ellini tried to shake her head, tried to reach out a hand to restrain him, but it was too late.

Maybe the proximity of the axe startled Elsie – maybe she thought she was being attacked – or maybe her desperation had been close to bubbling over anyway. She lashed out unthinkingly, clutching the air before him and prising it open. For a second, there were snowflakes on the cobbles – there was a blast of cold air.

Jack toppled into the darkness that had opened up in front of him, and Elsie drew the door shut on his screams.

Ellini stumbled and fell forwards, her own scream caught in her throat. There was nothing to fall into – or onto – except the cobbles now, and her shins slammed against them before she could catch herself. They were solid as flint, even though they were covered with a thin, powdery sprinkling of snow.

She scrambled up again, pawing at Elsie's skirts. "No!" Her breath steamed for a second, as the last of the cold departed. "Elsie, no! Bring him back!"

But Elsie was breathing hard through her nose, her jaw set, ready to lash out at anyone who pushed her.

***

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