Brother Diaz turned slowly around, head tipped back and mouth hanging open, dizzy with awe.

‘It’s so beautiful …’

The Chapel of the Holy Expediency might have been four times as high as it was wide, an echoing well of varicoloured marble lit by angelic shafts from a cupola high above. Carved niches held sculptures of the Virtues in human form, the walls crowded with paintings of the seventy-seven senior saints and a dizzying assortment of junior ones. There was a porphyry pulpit that wouldn’t have been a disappointing centrepiece for a cathedral, a gem-studded copy of the scriptures open on the lectern.

His lectern, he realised, awe beginning to melt under a warming glow of satisfaction. His pulpit in his chapel. He’d never been much of a preacher, admittedly. But in a place like this? He would make do.

‘It is beautiful.’ Baptiste draped an overfamiliar arm around his shoulders and pointed out a painting. ‘That Saint Stefan is by Havarazza.’

‘Really?’

‘I knew him, in fact.’

‘Saint Stefan?’

‘Havarazza.’ Baptiste modestly flicked a stray curl from her face and it immediately flopped back. ‘He painted me once.’

‘He did?’

‘I was between jobs at the time, serving as a lady-in-waiting to the Queen of Sicily.’

‘You … what?’

‘He was painting her during the days. I modelled for him in the evenings.’ She leaned close to whisper, ‘He wanted to do it nude.’

‘Er …’

‘But I insisted he keep his clothes on!’ Baptiste burst out laughing, then her laughter became a chuckle, and the chuckle petered out into awkward silence. She dabbed her eyes. ‘He died of syphilis.’

‘Havarazza did?’

‘And the Queen of Sicily soon after. Make of that what you will. I think the Duke of Milan has that painting.’

‘Of the Queen of Sicily?’

‘No, the one of me. He was a lovely man.’

‘The Duke of Milan?’

‘Ugh, no. He’s an absolute turd. I meant Havarazza.’ She considered that painting of Saint Stefan, smiling beatifically as toothy elves squashed his balls with red-hot tongs. ‘One of those truly pure souls you find now and again.’

‘I am … so sorry to hear that. About his death, that is, not his pure soul …’ Brother Diaz took the opportunity to slither from under Baptiste’s arm. He hadn’t been in such close contact with a woman for many years, and the outcome then had been far from a happy one. He placed a fond hand on one of several dozen giant votive candles, twice his height at least and thick as a tree trunk, wondering what it must have cost. He’d scored an unsung triumph negotiating a new contract with the chandler on his monastery’s behalf, so had a reasonable idea. ‘It really is a beautiful chapel …’

Pride was not numbered among the Twelve Virtues, but after being left to pickle in shame for so long he couldn’t help picturing the faces of his so-called brothers in the refectory when they heard the news. Vicar? Of an opulent and exclusive chapel? Inside the Celestial Palace? He imagined the monstrous scale of his mother’s boasting, the petty achievements of his actual brothers cast aside, the dishes passed first to him before they squabbled over the scraps—

The grating voice of Jakob of Thorn cut his daydreams off at the knee. ‘We won’t be spending much time here.’

‘We won’t?’

The knight had one hand under the lectern, wincing as he searched for something. There was a clunk, a grinding of gears, and the pulpit slid aside to reveal a hidden stairway, disappearing downwards.

‘Your flock are below.’

Brother Diaz swallowed as he peered into the inky darkness under the chapel, Cardinal Zizka’s mention of the howling night beyond creation making the hairs on his neck prickle. ‘Why below?’

‘Partly for their protection.’

‘Mostly for everyone else’s,’ said Baptiste, taking up a candelabrum with three flickering candles.

It was while following her downwards that Brother Diaz noticed all the daggers about her person. One could hardly miss the huge one strapped to her right thigh, and the only slightly smaller one buckled to her left, but now he noticed a curved one in the back of her belt, and the telltale glint of a pommel in the top of one tall boot, and, Sweet Saint Beatrix, two in her other boot.

‘You have a very great number of knives,’ he murmured.

‘I’ve found it’s a bad idea to run out.’ The candles gave her eyes a playful gleam quite at odds with the subject matter. ‘How could I stab anyone then?’

‘Do you stab people … often?’

‘I try to keep it to a minimum. Never stick your neck out, that’s my motto.’ She sighed. ‘But a life well lived will, perforce, feature some regrets.’

‘Perforce,’ murmured Brother Diaz, pointlessly. Behind him, Jakob of Thorn made the slightest pained grunt with each scraping footfall.

The walls changed as they descended. Dressed masonry gave way to the carelessly mortared brick of the foundations, which gave way to that strangely seamless grey stone, like the back wall of Zizka’s office, the candlelight throwing odd shadows from its humps and waves. Brother Diaz reached out, brushed it lightly with his fingertips. Very smooth, and very hard, and very cold.

‘The remains of the ancient city,’ said Jakob of Thorn.

‘Not much left above ground,’ tossed Baptiste over her shoulder, ‘but there are miles of tunnels below. No one knows how deep they go. All built by the Witch Engineers of Carthage.’

Brother Diaz snatched his fingertips away, touched them nervously to the lump in his habit made by the vial of Saint Beatrix. He couldn’t escape the irrational sensation that he was descending into the guts of a monster.

‘Ironic, really.’ Baptiste chuckled. ‘Long before it was the Holy City, it was … well …’ The light from her candelabrum fell on a weighty door, studded with iron, apparently scorched by flame and deeply carved with several interlocking circles of runes. ‘An unholy city?’ And Baptiste grinned over her shoulder as she rapped on it with her knuckles.

Brother Diaz steeled himself for unknown horrors as locks rattled and the door swung open – but beyond there was only a storeroom containing a fireplace and cookpot, several crates and barrels, shelves holding crockery and cutlery, and a huge bald man with a whale-oil lamp.

Baptiste frowned towards another door, still heavier and more rune-scored than the last. ‘All quiet?’

‘The wizard complained about his food,’ said the big man, in a thick accent, as he sat back down at a table and picked up a very small book. ‘But otherwise yes. This our new priest?’

‘Brother Diaz,’ grunted Jakob.

‘Ah, a Castillian?’

‘Leonese …’ Though insisting on the distinction seemed absurd under the circumstances.

‘Good to meet you. I’m Hobb. I look after the devils.’

Brother Diaz swallowed. ‘The what?’

‘Didn’t Cardinal Zizka give you the talk?’

‘She gave him the talk,’ said Jakob of Thorn.

‘They’re not really devils.’ Baptiste had gone to a long rack from which dangled at least a dozen bunches of heavy keys. ‘Not technically.’

‘You have a very great number of keys,’ murmured Brother Diaz.

‘Well, Brother,’ replied Baptiste as she plucked down one ring and began to sort through it, ‘we need a very great number of locks.’

Hobb laughed. ‘You’ll be fine. Just … stay back from the bars.’

‘From the what?’ muttered Brother Diaz, watching Baptiste tackle one lock after another.

‘Stay back from the bars, keep on your toes, trust nothing they say, and I’m sure you’ll fare better than your predecessor.’

‘What?’

‘That’s the spirit,’ said Hobb, planting one boot on the table and turning his attention to his book. ‘And don’t stick your neck out, eh, Baptiste?’

‘Never.’ Baptiste finally slid back two hefty bolts and shouldered the second door open, a faint breath of cool air issuing from beyond.

‘He looks after the devils,’ said Brother Diaz, in a kind of whimper.

‘But he’s from England.’ Jakob of Thorn ushered him over the threshold. ‘They’re all devils there.’

A hallway stretched off into the gloom, walls and ceiling a single semicircular vault of that melted-looking rock. The only light came from three ominously flickering candles in rusted sconces, falling on a set of archways in the left-hand wall. It might almost have felt like a wine cellar, had it not been for the grilles blocking the openings, bars of black iron thick as Brother Diaz’s wrist, well secured with yet more heavy locks.

He swallowed. ‘Are these … cells?’ Ancient ones, by the look of it. ‘What kind of prisoners did the Witch Engineers of Carthage keep?’

‘The righteous?’ Baptiste shrugged. ‘Or the really unrighteous?’

‘Those they hated,’ said Jakob. ‘Those they feared.’

‘And those they failed to understand.’ There was a scraping of chains from the nearest cell. ‘And little has changed in that regard.’ A man shuffled from the shadows. ‘New jailers, perhaps …’ He was an imposing figure, perhaps a patrician of Northern Afrique, his black hair and beard shot with grey. ‘But petty injustice, hypocrisy, and oppression are eternal.’ His air of outraged dignity was undermined by two facts impossible to ignore: his ankles were fettered by a heavy chain of black iron, and he was entirely naked.

Baptiste leaned casually against the archway. ‘Might I introduce the most recent addition to our little family. His name is Balthazar …’ She squinted at the ceiling, jingling her keyring on a fingertip. ‘I forget the rest of it.’

‘Balthazar Sham Ivam Draxi.’ The man flared his nostrils magnificently. ‘And it is a name that shall resound through history!’

‘Bit lengthy for an echo, isn’t it?’ said Baptiste, giving Brother Diaz a wink. ‘These sorcerers and their names—’

‘I am a magician, fool.’

‘Oh, I’m a dunce and you’re a genius.’ Baptiste smiled wider, gold teeth glinting. ‘That’s why you’re naked in a cage and I’m holding the key.’

‘Laugh while you can!’ The magician pressed his face to the bars and obliged Brother Diaz to take a cautious step back. ‘But no chain can restrain me! No spell can bind me! I shall free myself, and when I do my vengeance shall be the stuff of legend!’

He shook his fist as he worked himself to ever greater heights of outrage, and whenever he did his prick would swing about, and though Brother Diaz had no desire to see it, he somehow couldn’t stop looking at it, and had to hold up a hand to shield his eyes. ‘Must he be naked?’

‘He was scraping dirt from the corners of his cell and using it to write on his shirt,’ said Baptiste.

‘Would writing have been bad?’

‘It could’ve been very bad,’ said Jakob.

‘He is an infamous practitioner of Black Art,’ said Baptiste, ‘pursued by the Witch Hunters for nine years and found guilty as hell by the Celestial Court.’

‘Don’t they tend to … a little bit …’ Brother Diaz cleared his throat, ‘burn people for that?’

‘On rare occasions they are given a chance at redemption through a lifetime of service to Her Holiness.’

‘Redemption?’ snarled Balthazar Sham Ivam Draxi. ‘Ha! The distinction between Black Art and White is a patent artifice, born of wilful ignorance. They are drawn from one well. They even emerge in the same bucket! Then you blockheads dip in two cups and declare what suits your petty prejudices White and what defies your pitiful understanding Black when in fact they are one and the same—’

‘There was the matter of the dancing corpses,’ grated Jakob of Thorn.

‘And the bargaining with demons,’ added Baptiste.

Balthazar threw up his hands. ‘You bargain with one demon and that’s all anyone talks about!’

‘I need to sit down,’ muttered Brother Diaz, but there was no chair on offer.

The next cell was neatly furnished with a narrow bed well made, two faded rugs, and a shelf stacked with books, including a fine copy of the scriptures. But there appeared to be no one in it.

‘Sunny?’ Baptiste tapped at the bars with a man’s signet ring she wore. ‘You can come out.’

She didn’t jump from the shadows or wink suddenly into substance. She must’ve been standing there, in full view. But, for no reason Brother Diaz could explain, it was only when she turned towards him, breathing out with a long sigh, that he noticed her.

One could not possibly have overlooked that face otherwise. It was recognisably female, dusted with very ordinary freckles, but resembled a face reflected in a carnival mirror: impossibly narrow across the jaw and impossibly wide across the sharp cheeks, the nose far too small and the unblinking eyes far, far too big.

‘Saviour protect us,’ he breathed, making the sign of the circle over his chest. As if the magician hadn’t been bad enough. ‘It’s an elf.’

She stepped forwards, long fingers curling spider-like about the bars. ‘New priest?’ One might have expected an enemy of God to speak with a devilish hiss. The elf’s flat, high, normal little voice was quite the anticlimax.

‘This is Brother Diaz,’ said Jakob of Thorn.

The elf studied him, unblinking as a lizard. ‘Charmed,’ she said, and was no longer there.

‘Why …’ whispered Brother Diaz, his throat so tight he could hardly make the words, ‘is there an elf under the Celestial Palace?’

Baptiste waved towards the next set of bars. ‘For the same reason there’s a vampire under the Celestial Palace.’

This cell contained the most ancient-looking man Brother Diaz had ever seen. His body was hunched, face a withered mask, neck a flopping wattle, a few floating wisps clinging to his wrinkled pate. But his voice was rich with culture and refinement.

‘To undertake the labours,’ he said, ‘that those upstairs will not contemplate. I am Baron Rikard, and I can only apologise for my wretched decrepitude.’ He glanced towards the walking stick on which he leaned with one crooked, trembling hand. ‘I would bow but, with the stiffness in my back, I fear I might never rise …’

‘Pray don’t trouble yourself!’ Brother Diaz had never met a baron, had no notion where he might rank in Europe’s labyrinthine aristocracy, but felt the need to be on his very best behaviour. ‘It is my honour to—’

As he stepped towards the bars, Jakob of Thorn held out an arm to stop him. ‘Best keep your distance.’

‘You have no doubt already realised that Jakob can be exceedingly tiresome.’ The baron hobbled closer, flashing a smile. He had superb teeth for a man of his age, so pearly white and delicately pointed, Brother Diaz yearned to inspect them more closely. ‘I cannot tell you how desperately I am in need of good conversation, not to mention spiritual instruction. Your predecessor was no use whatever in such matters—’

Jakob of Thorn’s grating voice cut in. ‘Don’t get too close to the bars.’ Brother Diaz was surprised to see that, almost without noticing, he had taken another step towards the cage.

‘Honestly, Jakob, few people are more keenly aware than you how much blood a healthy young man contains. We all know he can spare a pint or two, eh, Brother Diaz?’ His eye had a playful sparkle and Diaz could not but chuckle. What a spirited and amusing old gent he was! How proud his mother would be, to learn he had a friend of such status! Whyever should he be kept in a cage? He had half a mind to wrestle the keys from Baptiste and unlock the gate—

Jakob’s voice was a warning bark. ‘Step back from the cage!’

Brother Diaz found, to his amazement, that he had stepped right up to the grille and was on the point of slipping his arm between the bars, right beside the baron’s withered face. He snatched it back as if from a blazing fire.

Baron Rikard curled his tongue around one pointed tooth and dragged it away with a disappointed sucking. ‘Well, you can’t blame a boy for trying.’

‘Did you ensorcel me just now?’ demanded Brother Diaz, gripping one hand to his chest with the other. ‘Was that ensorcelment?’

‘Manners might seem like magic in this company,’ grunted the vampire. ‘The two are not so far apart as some would prefer to believe. Rather like good and evil, in that regard.’

Brother Diaz gave an outraged gasp. ‘We can probably agree that feasting on the blood of innocents is on the evil side of the line!’

‘I will bow to your expertise. Or would if my back permitted.’ The baron gave a papery sigh as he turned away. ‘If vampires made sound moral judgements, after all … why would the world need priests?’

The next cell contained only dirty straw, a bucket, several sets of rather worrying scratches, and an animal odour that reminded Brother Diaz of a visit he once made, and instantly regretted, to a slaughterhouse in Aviles.

‘We had to place the last of our flock in more secure lodgings due to …’ Baptiste scratched her throat as if searching for the right words, which in someone who produced as many as her did not strike him as a good sign.

‘Unacceptable behaviour,’ said Jakob.

‘To put it very mildly. Sometimes we have more charges, sometimes fewer. The tasks assigned to the Chapel of the Holy Expediency lead to a certain …’

‘Churn,’ said Jakob.

Brother Diaz had no words. Honestly, he was finding it difficult to breathe down here. He was feeling dizzy. As if the ground might suddenly fall away. He struggled to loosen his collar once again. All he’d wanted was a comfortable living, somewhere sunny. To be taken seriously by the frivolous, regarded as wise by the unwise, and considered important by the unimportant. Instead, for reasons he couldn’t comprehend, he found himself called on to consort with scarred knights and part-time painter’s models, to face unspecified perils dire enough to threaten creation, all while not getting too close to the cages in which his congregation were kept.

‘I spent many years in a monastery,’ he almost whined, at no one in particular. ‘Away from everything, in the library, mostly, and a bit of work on the accounts, some weeding in the herb garden …’ God help him, he was starting to wish he was still there. ‘I really have … no experience with …’ Brother Diaz’s gesture encompassed the Witch Engineers’ dungeon housing the naked magician, the vanishing elf, the geriatric vampire, and whatever had been too badly behaved to be kept in such company. ‘All this.’

‘Your predecessor had experience,’ said Jakob of Thorn.

‘No one more,’ said Baptiste, sadly swinging her keys around one fingertip.

‘What became of them?’ asked Brother Diaz, desperate for a glint of light at the end of what was starting to seem a very dark tunnel. ‘Some new assignment?’

Baptiste winced. ‘Mother Ferrara was a very … rigid woman. Full of faith. Full of zeal.’

‘Huh,’ grunted Jakob.

‘But rigid things are prone … under extremes of pressure … to shatter.’

‘Extremes,’ echoed Brother Diaz, ‘of pressure?’

‘You see it.’ Baptiste placed a hand on his shoulder. If it was meant to reassure him, it failed spectacularly. ‘The Chapel of the Holy Expediency is no place to get … all dogmatic.’

‘Hmm,’ grunted Jakob.

‘In my experience – and my experience, did I mention …’ Baptiste slid her arm across Brother Diaz’s shoulders in an unsolicited embrace, the grip of one of her many knives poking him in the side, ‘… is considerable – if you treat everything like a fight you will, sooner or later, and probably sooner …’

‘Lose one,’ growled Jakob, glaring off grimly into the shadows.

Brother Diaz cleared his throat. He never used to need to clear his throat, but lately he was having to do it before every sentence. ‘I wouldn’t presume to challenge the breadth of your experience—’

‘Then we’ll get along famously!’ said Baptiste.

‘—but you don’t seem to have explained what, specifically, became of my predecessor.’

Jakob turned his grey eyes back to Brother Diaz, as if only now remembering he was there. ‘She’s dead.’ And he started to limp back the way they’d come.

‘Dead?’ whispered Brother Diaz.

‘As fuck.’ Baptiste gave his shoulders a parting squeeze. ‘She’s dead as fuck.’