Jack hurried down the stairs, hunched over the knife-box, pressing it firmly into his chest, even though he could feel its rancour. It had wanted to be taken.

Sam was down there, shouting at people. He snatched the front door key from Sarah, twisted it in the lock, and then slid the bolts across for good measure. The amulets were getting in his way, so he grabbed a handful and tore them down, making everyone in the hallway wince – even Sergei.

"Inspector, perhaps this is not the time to-"

"Chief Inspector," said Sam irritably. "And don't tell me you believe in them now."

"A wall of thorns has risen to a height of fifty feet around the city," Sergei pointed out. "It's impolitic to say what one does and does not believe at a time like this."

"No good locking doors anyway," said Jack, in a voice that was pressed determinedly into steadiness. "She'll get in through the mirrors and glass. We need to cover up anything in here that has a reflection."

They didn't ask who 'she' was. They must have known already. He didn't dare ask whether they could hear the furious chittering sound pouring down the stairs. He was afraid of being told it was all in his head.

He helped Sarah to hang tea towels and dust sheets over the mirrors, the paintings, the glass-fronted cabinets. Every framed photograph was turned face-down on the sideboard. He even untied the thick, tasselled ropes that kept the curtains back, and they fell together with a heavy, velvet whump. There was something unpleasantly final about that sound – as if the curtains were never going to be opened again.

Then he turned to Elsie, who was fiddling with the phial he'd given her, trying to unscrew its lid. Now Jack had the time to take her in, he noticed that her shoulder was bound up in bandages, though there was no trace of blood soaking through the gauze.

"You felt it?" he demanded. "When she got shot?"

She was very weak. Danvers was supporting her underneath one elbow, but her attention was completely taken up with the phial.

"What is it?" she whispered to herself. "I know it."

"Please be careful, Elsie," said Danvers. "The lid's almost off, you might spill it."

"It's of my world," she said, half-laughing. "It will obey me."

The lid came loose, and the white powder started to fall, but then it changed its mind in mid-air and swarmed up to Elsie's beckoning fingers.

It formed a kind of cloud around her hand. She cupped it and felt its edges, teasing bits out, coaxing it into a kind of shape like – a little tusk? A small, gently curving thing, anyway. The dust held the shape, coalesced and hardened, and then dropped into Elsie's hand as a solid object.

"A bone?" said Danvers.

"It looks like a rib," Sergei volunteered. "A human rib."

"I know it," Elsie repeated, almost inaudibly.

Danvers laid a hand on her shoulder. "Elsie, didn't Dr Faustus say that was how she cut herself off from you? By removing one of her own ribs?"

Elsie formed her mouth into an 'o' shape but said nothing. She continued to turn the bone this way and that in her hands, as if she could see the way it caught the light.

"Wait," said Jack, "does that mean you can control her now? She's not cut off from you anymore?"

"No, I-" Elsie shook her head. "I can't control her. The rib would need to be put back. But I can see her now – that is, I can see the hole where she should be. A sort of negative space." She shook her head again – in wonderment, this time. "She's... she's just like me."

Danvers's hand tightened on her shoulder. "She is not just like you."

"What about the letter?" said Jack, trying to find the silver-lining, the hopeful sign that would unclench his throat and smooth down the hairs on the back of his neck. "Have you read it?"

"Oh yes," said Elsie, as if she'd just remembered. She turned to Danvers and handed him the rib bone. "Will you read it to me?"

Danvers's expression went from outraged to uncomfortable. "It's addressed to Miss Syal. I don't know that I should-"

"Oh, for God's sake!" Jack shouted. "She told me to bring it here!"

"She's in the city?"

"Oh yes," said Elsie helpfully. "And in tremendous pain."

Jack clenched his teeth. He briefly imagined grinding them down to powder, through sheer frustration, and Elsie re-forming them with a wave of her hand.

Sergei stepped forwards, pale behind the moustache. "Elsie, what if I were to give you something for the pain – something to stave off infection? Would it help her?"

Jack twisted his mouth into a smile. It was a genuine smile, but the logistics of smiling were not coming easily to him at the moment. "Sergei, you're a wonder. Sarah, get his bag. Danvers, read the god damned letter."

With great dignity, Danvers lifted the envelope and extracted the letter. He cleared his throat, left what Jack considered to be a spitefully long pause, and then started reading.

After two or three sentences, Jack took up station behind him and read over his shoulder, his frown deepening as his eyes slipped down the page.

It wasn't difficult to work out what had happened from those casual, self-important words. It wasn't even really out of character. Oh, Robin sacrificing himself was out of character – so out of character that it cast a pall of unreality over every word that followed – but it must have been spectacularly dramatic. It would have given ample scope for indulging his malice, his vanity, his capacity for nasty forethought. He could just picture the burning tower of Pandemonium, the windows blowing out in a hailstorm of glass, the birds sweeping in terror across the sky.

And he had always known that Robin loved Ellini, in his twisted, possessive way.

No, Jack wasn't as incredulous as Ellini had been. He was angry – there was too much flippant talk about frightening her, hurting her, 'liking to think' she would survive. He would never have been so careless with her safety.

But it wasn't anger that was burrowing into his stomach now. And it wasn't pity. Robin didn't deserve pity, and Jack couldn't have brought himself to feel any for him anyway. It was a hollow, hopeless feeling, like the wind whistling through deserted halls.

He didn't miss Robin – he didn't think so – but... well. Robin had always been there, and he had always been selfish. His selfishness had been one of the few certainties in Jack's life, like his love for Ellini. And Myrrha had managed, at various times, to put an end to both of them. Myrrha just ended things.

He was aware of people talking around him – marvelling, perhaps, at the contents of the letter. He tried to train his attention on their words, but it was difficult. Robin was gone, and he felt relieved and bereaved at the same time.

"That's why she's here," Elsie was saying. "Because she needs the knife to resurrect him."

"And while she's here, she can be killed," said Danvers. Jack registered that bit, because it was so unlike Danvers to be talking in a calm and steady voice about killing people. "You still have the sword, Inspector Hastings?"

"Chief Inspector," Sam insisted, his teeth clenched on every word. "And I'm not going to-"

But he was drowned out by Elsie, who bustled on as if she were a little girl discussing holiday plans. "Then all we need is Mrs Darwin."

A silence succeeded this comment. And that was when it dawned on Jack that she should have been here – that she could have been standing blithely in front of a mirror all this time – that there might be a charred and blackened hand clasped around her throat.

His mind went through five or six horrific scenarios before Sergei said, hesitantly, "She's in the...glass laboratory."

They turned to look back up the staircase, and heard the sound of breaking glass.

Jack ran up the stairs two at a time, with Sam hurtling behind him. He was faintly aware of the knife-box, still clasped to his chest, and the fact that he shouldn't be bringing it into a room full of glass objects, any one of which might have Myrrha's eyes shining behind them. Did she still have eyes, he wondered? Or had they been melted out by the flames?

In any case, there was no time to give it to someone else for safe keeping. There was no-one else he particularly wanted to make into a target. And they were at the top of the stairs now, Sam barging past him, flinging the door open.

They both stopped on the threshold, stilled into uncertainty by what they saw. The breaking sound must have been from one of Alice's long-necked flasks, because she was holding two long shards in her hands, thin and pointed like icicles. Their jagged edges were slicing into her palms, but she was holding them quite steadily.

The blood was bad enough, dribbling down her forearms and dripping off her elbows, but her face...

Alice's face had never been blank or purposeless. Her jaw had never been slack. She had never shuffled forwards, drooping from the shoulders, her arms held out with a kind of wretched rigor mortis rather than muscular strength.

She stared at them without blinking, without recognition, and then stepped forwards, holding her shards of glass like knives.

Jack saw Sam fumbling for his revolver, and flung an arm out to stop him. "No. It's not her, it's Myrrha."

"Well, what's your brilliant idea, then?"

Jack turned to her and tried to smile. "Alice-"

But the horrible, lurching gait masked a surprising quickness. She jabbed the glass knife at his face – so suddenly that he had to jerk backwards and hit his head against the door.

He ducked under her next swipe, drove his shoulder into her mid-section, and brought her down. She was cursing with the same chittering sound he'd heard on the staircase – like millions of insect-wings flapping and scraping against each other.

For a moment, he had her. He pinned her struggling arms to the floor, resisted all her attempts to buck him off, and took a deep, shaky breath while she swore and spat at him.

Then something exploded close to his face – one of the glass flasks on the table must have burst – and without thinking, he raised his arms to shield himself.

She lurched underneath him, and he heard her improvised knives slicing through the air. He rolled backwards, crunching through the glass in his haste to get away. He could feel the nip of a dozen little splinters through the fabric of his shirt.

Alice threw herself after him, and raised her knives for another swipe, but suddenly Sam was there – he must have crawled round behind her – pinning her arms to her sides and struggling to hold her as she kicked and lurched.

"Hold her steady," Jack shouted, getting to his feet.

Sam's face was red over her shoulder. She was fearsomely strong. One of her arms had already worked its way loose, but she was flailing it at Jack, rather than swiping behind her to cut herself loose. Jack was suddenly thankful that he'd taken Gram's lacquered box into the room with him, because it was clearly commanding every bit of her attention.

He tried to steady himself, tried to take a deep breath and plant his feet. He needed to knock her out without permanently damaging her, and that was hard enough to accomplish even when your assailant was standing perfectly still. Besides, he wasn't sure she would be herself when she woke up. For all he knew, she was Myrrha's forever, which meant that he and Ellini had already – irrevocably – lost.

"Whatever you're going to do," Sam grunted, "you'd better do it now."

She was trying to force him backwards, at the same time as flailing her knife at Jack. She brought both her legs up to the table and pushed, forcing Sam back against the sideboard. Another flask exploded behind him, and he clenched his teeth, but didn't loosen his hold.

Jack couldn't help smiling. He was tough, this guy. Nobody should have been surprised by the scenes at the martyrs' memorial. Of course Sam Hastings would survive a fall from a first-floor window and stay conscious long enough to be bitten by 'the biting kind'.

Jack aimed a punch straight between Alice's flailing arms – they were both loose by now – and struck her in the face.

Her head drooped. Her weight slackened in Sam's arms. Jack had time to note, with a serene kind of hysteria, that he had managed to break her nose this time. And then everything exploded.

Every flask and test-tube and curly-necked bottle burst open, one by one, and sent a hailstorm of glass into the air. He didn't know whether to shield himself or shield Alice. With his eyes pinched shut, and a back full of stinging splinters, he helped Sam bundle her under the table, and tried to keep her head covered.

The noise was deafening. He was sure for a moment that one of the glass splinters had pierced his eardrum, letting in a whirling sinkhole of sound. It wasn't just the tinkle and crack of broken glass, but that chittering again, louder than ever. It occurred to him suddenly that every splinter had a reflective surface, and the glass could never break into small enough pieces to keep her out.

Even when he was reasonably sure there was nothing left to explode, he still heard intermittent crashes, as the glass settled and slid onto the floor. Finally, there was silence, apart from Sam's heavy breathing – a reassuring sound, even though it usually presaged a lot of shouting.

Jack was suddenly struck by how glad he was that Sam was here. He felt breathless and giggly with horror – possibly blood-loss too. His shirt was wet in several places, and would probably slide right off his back when he stood up, sliced into ribbons by the flying glass.

He breathed out, leaned his head back, and grinned at Sam. "Now would probably be a good time to tell me you forgive me."

Sam glared at him. "It would, if I did."

Jack shook his head, still smiling. "Oh, Sammie. I did everything I could not to kill you."

"Yes, and that was selfish of you, because what you did was worse than killing me. You made me bad at my job."

"Made you? I didn't make you run after that letter."

"But you knew I would!"

"That's not the same thing."

Sam narrowed his eyes, but he didn't look as though he had the energy to shout. The sight of Alice with her slack jaw and deadened shuffling must have spooked him too.

"Nobody is going to die," he said at last. "Help me get this Myrrha woman out of the city without anyone dying, and I'll forgive you. And, if someone does die, that's you being bad at your job, and we'll be even."

Jack stared at him for a moment, his smile finally slipping. "When you say 'Nobody is going to die', you mean apart from Myrrha, don't you? Sammie?"

Sam didn't answer – and Jack was about to let go of Alice and seize him by the shoulders, but a commotion at the doorway stopped him. Elsie, Danvers and Sergei were poking their heads round the door, and he still wasn't sure that the threat had passed and there was nothing left to blow up in their faces.

"Get back!" he yelled.

"Uh... we have visitors," said Sergei, his eyes lingering on the mess of blood and glass on the floor. "I thought it would be all right to let them in. They don't seem to be demonically possessed."

Jack scrambled out from under the table, crunching glass underfoot, and craned his neck to see past Sergei down the staircase.

Three women were standing silhouetted in the light from the open front door. They were drooping and blood-stained, and one of them had her arms folded in a very characteristic way, but Jack had never seen a lovelier sight.

He half-ran and half-slid down the stairs, knocking people out of his way – he didn't even see who – until he was standing in front of Ellini. The arrow had been taken out of her. In its place was a bandage dyed red with blood.

For a moment, once again, they saw their own expressions reflected in each other's faces. He supposed he looked as bad as she did. The flying glass shards had caught him in a hundred places, and there was definitely blood on his neck, soaking into his collar.

But they were both smiling – at least, she was, and Jack felt a corresponding tightness around his mouth, so he supposed he must have been, too.

He scooped her up one-handed, trying to avoid the shoulder-wound, and kissed her upturned face in as many places as he could reach. Her skin was salty from sweat or tears, but she felt firm under his hands, and her eyes had their usual determined focus. She was all right.

"And you've brought my Sita," he said, bending down and transferring his kisses to the little girl's forehead. "Things always look better when I've got my Sita."

"Jack, a big, burnt arm came out of the mirror and tried to grab me, and Leeny fought it with an axe-"

"Mr Danvers?"

It was Elsie's voice, half-petulant and half-alarmed, as if she had reached for his hand and not found it. And Danvers wasn't there. He wasn't on the staircase, or standing in the doorway to the Faculty Lounge.

With a growing sense of unease, Jack launched himself out of the front door and onto the steps. There was no Danvers to be seen at either end of the street, and Elsie was calling his name with real panic now. The sound of it was like fingernails down the blackboard of his soul. Danvers had never failed to come when she called him.

Behind him – from under the dustsheets that cloaked the mirrors, from the face-down photographs on the sideboard, and maybe even from the varnish on the banisters – the chittering resolved itself into a voice. It said:

"Meet me at the spot where the martyrs were burned. Bring the knife. Bring Ellini. We'll see if we can negotiate a civilized exchange."

***

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