‘And then you’re dead.’ Foison walked to the foundry door, but then paused. ‘And Professor?’

  Trooste forced a patient smile. ‘Anything.’

  ‘You wouldn’t know how empty shell casings came to be littering the top of your stairs?’

  ‘Shell casings?’

  ‘From a revolving pistol.’

  ‘I’ve no idea. I have no weapon.’

  ‘That is wise. The way your day is going, it would only be used against you.’

  As soon as Foison was gone, Trooste sagged against the table, pale with fear. ‘I did what you asked – wait – wait! Where are you going?’

  Mahmoud raced from his hiding place to the foundry room. Svenson hesitated, taking a step towards Francesca, but then followed the dark man. He found Mahmoud crouched at the second exit door. With silent care Mahmoud eased its bolt home, blocking any re-entry.

  ‘That cold-eyed Asiatic will have my life.’

  Trooste had joined them, but the Doctor paid no heed. Above the foundry’s stone trough hung a metal rack, and there, like cakes from a baker’s oven, lay three blue glass books.

  ‘What in heaven …’ whispered Mahmoud.

  ‘O yes,’ agreed Trooste. ‘Aren’t they glorious? Just made this morning, by Lord Vandaariff himself, every one untouched and pure –’

  Svenson tried to control his voice. ‘Mahmoud, take hold of the Professor. Do not touch or look into these books. A glass book brought your mistress to this pass.’

  ‘But what are they?’

  Against the wall lay a stack of leather cases. Svenson opened the topmost, noting with grim satisfaction that its interior was lined with orange felt. Equally to his purpose was a pair of iron tongs, wrapped with cloth. As the others watched, Svenson carefully lifted one of the books and set it in the case. He snapped the case shut. Mahmoud held another ready, but Svenson shook his head.

  ‘Put it down. Turn away.’

  ‘O no.’ Trooste began to sputter. ‘No, no – good God, the effort! He will kill me! I beg you –’

  Svenson flipped the second book off the rack. It struck the edge of the trough and shattered across the stone floor. Trooste howled, and only Mahmoud’s strength kept him from tackling Svenson. Svenson seized the third book.

  ‘You cannot!’ Trooste writhed. ‘I swear – I will be hunted down –’

  Svenson heaved the book onto the stone. He broke the shards under his boots. He stumbled. He was growing light-headed – there were fumes. He dropped the tongs and clapped a hand over his nose and mouth.

  ‘Get out – hold your breath!’ As the others fled, the Doctor stamped again and again on the broken books. He careened into the main chamber, slamming the door behind.

  ‘Barbarian,’ spat Trooste.

  ‘You have no idea.’ Svenson rubbed his stinging eyes.

  ‘But, Doctor, I don’t understand.’ Mahmoud pointed to the leather case in Svenson’s hand. ‘If those books are so terrible, why keep that one?’

  ‘Because the Professor is correct. We’ll need a weapon.’

  Svenson interrogated Trooste about the machinery, keeping one eye on Francesca – gauging the veracity of the resentful man’s answers by the distress each nugget of information provoked in the girl. Caught between Svenson’s bitter resolve and the spectre of Mr Foison, the Professor became more and more anxious. By the end Trooste barked his replies, flinching in advance at the child’s grunts and soot-coloured drool.

  But in that half-hour Doctor Svenson learnt more than he had ever desired about indigo clay: conduction, amplification, and the power Trooste termed ‘reciprocal cognition’. He now perceived in the tangles of wire and hose a mechanical intention: the operative essence of indigo clay eluded him as much as ever, but laid bare were the physical means to translate memory into a glass book, to infuse a book’s contents into an empty mind, to overwhelm a victim’s will with the Process – each action a relatively straightforward matter of force and direction. The restoration of Madelaine Kraft, however, depended on knowledge Trooste did not have.

  Svenson had seen the toxic effects of prolonged exposure and bodily ingestion, but Madelaine Kraft’s affliction could not be put down to physical proximity – it was not as if blue glass had touched her brain. Moreover, she could form new memories – so how to explain her continued vacancy? Perhaps the chemical exchange wherein blue glass captured memory carried a charged violence, enough to leave the psychic equivalent of scar tissue. Could the power of these machines overcome that artificial barrier? And if so, would the action reveal her memory intact, like a forgotten city beneath a dam-formed lake? Or would the necessary intensity simply destroy her?

  Svenson gazed down at Mrs Kraft and squeezed the woman’s honey-coloured hand. Whatever he was supposed to find, there was precious little time in which to do it.

  ‘She will be herself once again,’ he said. ‘Is that not right, Francesca?’ The girl had brought her knees up to her chest and sat rocking, dirty ankles exposed. ‘Perhaps you might tell Mrs Kraft yourself.’

  Francesca shook her head, lips tightly shut. Hating the lie, he smiled encouragingly. The girl hiccupped and shook her head to stop him talking, but Svenson kept on.

  ‘I know you feel ill, but you must trust the Contessa. Look at Mrs Kraft – or, even better, take her hand.’ He lifted the child to the table, ignoring the worry on the faces of the other men. ‘Excellent, now, think of what we know … when I look into a glass book, which is to say, when I touch it with my gaze, this contact allows its entrance to my mind –’

  The child’s hacking spattered black onto Svenson’s sleeve.

  ‘Doctor –’

  ‘Please do not interrupt, Mr Mahmoud. Physical contact is different, Francesca, yes? For example, I was able to remove glass from Cardinal Chang’s lungs with an orange liquid that dissolved the glass into phlegm, so it could be expelled. But even if we possessed that mixture –’

  ‘Bloodstone,’ Francesca croaked.

  ‘Bloodstone?’ Svenson had never heard the name.

  ‘An al-alch …’ She stumbled on the words with an unhappy squeak. ‘… alchemical catalyst.’

  ‘Compounded out of what – what elements?’

  Francesca choked again, spraying Svenson’s coat. Mahmoud turned on Trooste. ‘Do you have any on hand? Bloodstone?’

  ‘Lord Vandaariff has procured a broad range of chemicals –’

  Trooste indicated an apothecary’s cabinet, a tall draught-board of tiny drawers. Mahmoud leapt to it, opening an entire row. Svenson carried the child over, so she might peer inside, but Francesca shook her head at each. Her eyes were wandering and wild. Mahmoud slammed the drawers as they went and wrenched at the next row.

  ‘What does it look like?’ he asked.

  ‘The liquid was orange,’ said Svenson. ‘I have seen an orange metal as well, but that was refined, and no doubt an alloy –’

  Francesca dismissed this row as well. Mahmoud set upon another and growled at Trooste, ‘Have you no idea?’

  ‘I am sorry, good fellow,’ Trooste replied. ‘Lord Vandaariff is not one to share a secret. Naturally I regret Mrs Kraft’s condition – she has been a friend to the Institute – although, as a regular visitor, and I am not alone in this opinion, one might merit a reduction –’

  Mahmoud squared on Trooste, but Svenson caught his fist before it could swing. The sudden gesture loosened his grip on the girl and she sagged forward. Francesca inhaled, nostrils flaring, and began to whine like a chastened pup. The nearest drawer was filled with brownish rock. Svenson held a chunk to her nose. She gagged and squirmed away, unable to breathe.

  ‘You will kill her,’ cried Trooste. ‘Jesus Lord –’

  Svenson ignored him. ‘Francesca! What do we do? How do we use it?’

  Francesca met his eyes, fearfully, plaintively, and opened her mouth wide, as if she were showing him a broken tooth. Black fluid poured down her chin.

  ‘Dear God!’ Trooste protested.

/>   ‘It is nothing at all,’ Svenson snarled. ‘Mahmoud – bloodstone – mortar and pestle, grind it as fine as gunpowder –’ He thrust a finger at one of the brass gearboxes. ‘Professor Trooste, we will need that machine. Make it ready at once.’

  ‘You have no idea –’

  ‘Move, damn you!’

  ‘The smell …’ Francesca’s voice was a stricken complaint. Svenson wiped her face.

  ‘Do not mark it, my dear – two minutes more and we shall whisk you to clean air –’

  ‘The smell …’

  ‘Yes, I am so sorry –’

  ‘The smell is when.’

  Francesca’s eyes rolled back into her skull.

  The child lay shivering in Svenson’s greatcoat. She would not revive.

  ‘A terrible shock,’ he muttered, ‘a marvel she could help as she did. We will let the poor thing rest, and get her to safety as soon as possible.’

  Mahmoud’s silence was its own condemnation, but the steady grind of the pestle bespoke the man’s determination. Trooste cleared his throat into a closed pink hand.

  ‘I believe Mrs Kraft would be better restored with a garlic soup.’

  Mahmoud merely lifted the mortar with the pounded bloodstone for Svenson to see.

  ‘That is excellent, I’m sure. If Professor Trooste will deign to assist …’

  Trooste did so, adjusting the brass knobs on a gearbox, though not without a glance at the door. Mahmoud’s worry seemed no less acute.

  ‘Why has no one come?’

  ‘We do not know what has happened in the courtyard.’ Svenson poured a handful of ground bloodstone into the gearbox.

  Trooste frowned. ‘If there were a crisis, Mr Foison would have told me.’

  ‘He trusts you that much?’

  ‘He trusts no one – but Lord Vandaariff has shown every confidence. Why not stop all of this and let me address him on your behalf?’

  Svenson made sure of the hoses and wires. The black rubber mask left only Mrs Kraft’s mouth exposed to breathe. Trooste inserted a heavy lozenge of blue glass into the crucible chamber. Svenson connected the copper wire to the crucible leads.

  ‘Mahmoud, please step back from the table.’

  ‘What will happen to her?’ asked Mahmoud. ‘All of this wizardry –’

  ‘She will be cured.’

  ‘She won’t,’ declared Trooste.

  ‘Correct me if I am wrong, Professor. This’ – Svenson pointed to a switch inside the wooden box – ‘ignites the crucible. The initial charge sent through the glass is amplified by passage around the chamber and feeds back again into the gearbox. There the collected charge reacts with the bloodstone, and – when the gearbox valve is opened – infuses the subject with its properties.’

  ‘That is the map of it,’ replied Trooste. ‘But a map is only half of the matter. How much bloodstone? You’re only guessing. Just as you take the word of an incoherent child that it’s bloodstone to begin with – or that bloodstone isn’t fatal. How long do you wait before opening the valve? Not long enough, and the force is too weak. Too long, and the charge alone will kill her.’

  Mahmoud looked to Svenson for an answer. He had none.

  ‘That is the truth!’ Trooste snapped.

  ‘Why did that woman send you?’ Mahmoud’s question was a dagger between Svenson’s ribs. ‘Madelaine Kraft is nothing to her. I cannot believe in her kindness.’

  Svenson spread his open palms. ‘I do not ask you to.’

  ‘Then you are here to kill her?’

  ‘If that were true, why drag you all this way?’

  ‘For your science.’

  ‘Not mine, Mahmoud.’

  ‘She will die on this table,’ insisted Trooste.

  ‘She will never heal as things stand,’ said Svenson gently. ‘She will waste to nothing.’

  Mahmoud gazed helplessly at the woman, limbs bound and face obscured, only the red mouth visible. In an instant of clarity Svenson saw the isolated line of Madelaine Kraft’s jaw exactly mirrored on Mahmoud’s younger, darker face. He was her son.

  ‘Do it.’ Mahmoud’s voice fell flat and hopeless. ‘She would rather die than live like this. Do it now.’

  Svenson pulled the switch. A rattle of current, like a rolling volley of musket-fire, leapt along the lines of copper wire, and the sharp stench of indigo clay burnt the air. The metal pipes that covered the walls took up the vibrations, escalating until the entire chamber throbbed with a deafening roar. Svenson clapped his hands over his ears, but it did not stop the pain. Like a fool he remembered the Comte’s brass helmets – and there they were, across the chamber, in a row. If only either he or Trooste had known what they were doing! But it was too late to reach them. Madelaine Kraft’s limbs tore against the restraints and her mouth gaped in an unheard howl. Mahmoud had a fist in his mouth, eyes fixed on his mother. Svenson lurched to the gearbox, ready to open the valve. Trooste tugged at his tunic, waving frantically. Svenson shook his head. Trooste tugged again. Madelaine Kraft arched her spine, rising off the table, higher, higher, until it seemed her bones must snap –

  He almost missed it, between Trooste’s attempts to shove him aside and the hammering noise, so loud he could scarcely link one thought to another. The current flooded the bloodstone, shaking the bolts that held the gearbox – then there it was, a burst of scent, bittersweet and musky, a rawness in his nostrils –

  The smell is when.

  Svenson opened the valve. The black hoses flared to life. Madelaine Kraft’s twisting body went stiff, fingers splayed, jaw wide, the waves of force pouring through –

  The current from the gearbox died as quickly as a candle flame, the bloodstone spent. Trooste leapt forward, closed the valve and groped in the box for the switch. The roar in the pipes fell away. The blackened wires snapped their final sparks and set to gently smoking.

  Svenson fell to the table, ears pounding. Mrs Kraft’s pulse was racing but strong. With a cry of relief he waved Mahmoud to him and together they peeled the mask from her face. She bore welts where it had pressed into her skin, but her eyes … her eyes shone with a life Doctor Svenson had not previously seen.

  ‘Mrs Kraft?’ He could not hear himself, but it did not matter. She nodded. Mahmoud freed her limbs and raised her to sit.

  ‘Merciful heaven,’ she managed. ‘I have been at the bottom of the sea. O my dear boy.’

  She buried her face in Mahmoud’s shoulder and his strong arms pulled her close. Mahmoud leant down, face to her hair, a spill of tears on his dark cheek.

  ‘Now,’ Mahmoud whispered. ‘Now we pay them back.’

  Svenson hurried to Francesca. The girl was cold to the touch, her breath shallow. He tapped her cheek to no response.

  ‘Is she alive?’ asked Trooste.

  ‘Of course she is!’ Svenson crossed to the still-open square drawer and heaped another load of bloodstone into the mortar. He sat on a bench and began to grind it furiously.

  ‘Why do you need more?’ asked Trooste. ‘A child cannot withstand that current.’

  ‘I am aware of it,’ Svenson replied tightly. Mahmoud murmured to Mrs Kraft, yet her gaze fell on Doctor Svenson, to his discomfort.

  ‘Then for whom?’ Trooste pressed. ‘Not one of us!’

  ‘No.’ Svenson filled a stoppered flask with the rust-coloured grains and tucked it inside his tunic.

  ‘Then what?’ complained Trooste. ‘For God’s sake will you not leave? They will think I have betrayed them – my entire prospects of advancement –’

  ‘Are bankrupt. Lorenz, Fochtmann, Crooner – did you know Crooner?’

  ‘Everyone knew Crooner – ludicrous fellow –’

  ‘Crooner died with both arms shattered at the elbow, turned to blue glass.’

  ‘Well, exactly – that is Crooner all over –’

  ‘Don’t be an ass!’ The Doctor pulled on his greatcoat. ‘Listen – we will climb these stairs. Mahmoud must help his mistress, I must carry the girl. We cannot drag you
. But Vandaariff must not know what we have done.’

  ‘Lock me in a cupboard, I will say I saw nothing –’

  ‘You will divulge every detail.’ Svenson pulled out the revolver. The Professor swallowed, his wide throat bobbing.

  ‘B-but I have helped you –’

  ‘And so I ask you to come with us. If you do not, I will shoot you or bury your mind in this last glass book.’ The words were inhuman, but had he any choice?

  ‘No. I would not wish it on a fiend.’ Madelaine Kraft’s voice carried an authority, however weak. ‘If the Professor will not leave this business, Mahmoud could perhaps prove his resistance to our trespass … say, by shooting his leg.’

  ‘Through the knee?’ offered Mahmoud.

  ‘Hardly sufficient,’ she observed. ‘Both knees would be better.’

  Trooste blanched, at which Mrs Kraft smiled, and the moment of violence was past. The ease of her intervention seemed from another world – as distant to Svenson as allowing himself satisfaction for her cure. The Doctor stuffed away the revolver and slung the leather case over one shoulder. He lifted Francesca and stumped to the door.

  For once the height of a staircase did not disrupt the Doctor’s thoughts, distracted as he was by the question of what to do next. They clustered on the upper landing, all save Mahmoud panting from the climb. Svenson put an ear to the door, but heard nothing.

  ‘If the guard has returned, we must pull him inside – throw him down the stairs, anything for silence. If he has not, then I suggest we run for the same window we came from –’

  ‘We will be seen from the rooftop.’ This was Madelaine Kraft. Her tone carried no criticism, but Svenson felt nakedly at fault.

  ‘Then I will charge the gate. While they surround me, Mahmoud runs for the window with you and the child –’

  ‘They will shoot you dead, then the rest of us from a distance. Where will your mission be then? Or our revenge?’

  Svenson could not think. He could not look down at the girl. He felt the grain of the wooden door against his forehead. ‘I am open to suggestion.’

  ‘I will go with the Professor. He is known, and if I am noticed, the reaction will at least not be immediately hostile. If he betrays me, I will cut him down. Mahmoud?’