‘It was started over a century ago,’ Vale explained. He gestured down the row of elegant pale houses, their black iron balconies gleaming with reflected light from the street lamps. ‘Lyall Mews. The properties were all owned by the same noble family. Unfortunately, their heir wasn’t as good with cards and dice as he’d thought, and the family ended up mortgaged to their eyebrows. They eventually signed a contract with a syndicate, permanently renting the entire set of cellars to them for a nominal fee, though they kept the houses above.’

‘And that same syndicate still owns the contract,’ Singh agreed. He’d turned up his collar against the night air, and his moustache bristled above it. ‘Even if all the houses are owned by different families these days. How do you want to handle this, Mr Vale? There are two main exits, one at each end of the market. We don’t want to risk our quarry bolting out of one, the moment we walk in the other.’

‘You think Zayanna will actually be here?’ Kai asked.

‘It’s possible,’ Vale said. ‘Not very likely, but certainly not impossible. Or we can question stallholders who might have seen her. She is Fae, after all. And even if she doesn’t actually need any more pets, she may not be able to resist the urge to come shopping.’

He pointed down the street again towards a square of light on the pavement, indicating an open door. ‘That is one of the two entrances to the market. The other is beside us. There are approximately three vendors who might have supplied king baboon spiders, giant Asian hornets and snakes – you did mention that she was fond of snakes? If two of us use this entrance, and the other two enter by the other door, we can work towards the middle. If we check with vendors on the way, then we can intercept the lady if she is present; and we may hope to find her delivery address, if not.’

Irene was not wildly enthusiastic to find herself heading down to the far entrance in Singh’s company. Singh was too professional to show it, but she didn’t think he was happy either. But Vale had proposed the division of labour, and Kai had agreed to it.

Are Singh and I supposed to realize each other’s good points while working together and bond over the job? She was perfectly well aware of Singh’s good points. He was intelligent, professional, ethical, and probably a better influence on Vale than she was. It was more a question of Singh disliking her – on the grounds that she was a book thief from another world who’d broken the law more than once, and who had put Vale in danger. And she couldn’t really argue with that.

The open door at the far end of the street also leaked light out into the foggy night, together with a mixture of aromas – an overriding smell of cheap incense, and beneath it undertones of hay, mould and dung. The room behind the door was small and bare, lit by a single ether-lamp, and might once have been a storage cupboard. Two large men were sitting behind a table, anonymous in overcoats and mufflers. A cash-box sat on the table in obvious invitation.

‘How much is it?’ Singh asked. He’d pulled his hat low over his eyes and, like the men, he’d now covered his mouth and chin with a scarf. Irene had collected a spare overcoat and veil from Vale’s rooms and was similarly well covered. The whole thing was verging on the ridiculous. If this was the general standard of dress for the Belgravia Underground Market, no wonder people with more money than sense spent their time and cash here. Still, it did increase the chances of them finding Zayanna here. She’d love it.

‘Five guineas each,’ the man on the right said. It wasn’t an attempt at bargaining. It was a simple statement of fact. Irene revised her opinion of this place’s customers, placing them even higher up the idle-rich scale of finance.

Singh and Irene dropped money into the cash box, and the man on the left nodded them towards the inner door.

Noise washed over them as they stepped inside, and the smell made Irene draw her veil closer across her face. The long stretch of cellars wasn’t well lit: the occasional lamps were turned down or muted with coloured shades, and the far end of the market was hidden in shadows. The cellars were wider than she’d expected, and she realized they must run under the front street on one side and also out under the back gardens of the houses on the other side. Vendors had laid out their stalls in little islands in the centre of each cellar, or jostled each other along the walls. Some displayed tanks and aquariums, with snakes, lizards and fish. Others showed off gauze-covered boxes and hives, or cages, or even animals on small leads. A pair of white owls in the corner overlooked the room with furious yellow eyes, glaring down like offended deities, their legs tethered to their owner’s table by paired chains. The clothing of the shoppers ranged from the expensive to the ridiculous, but given the time of night and the fog outside, most people were muffled in heavy coats.

‘Miss Chayat’s stall first,’ Singh said, nodding over to the right-hand wall. ‘She’s one of the main insect suppliers, I believe.’

The stall in question was obvious, standing between purveyors of armoured lizards on the right and of Siamese fighting fish on the left. Its shelves were filled with tiny cages, each containing a single insect or a pair of them, walled with gauze and sealed with wax. The air around it hummed with the sound of struggling insects. The stallholder herself was as untidy as her wares were neat, with long greying hair that tangled around her face and blended indistinctly into her tattered shawl and beige dress. She peered at them suspiciously as they approached.

‘King baboon spiders,’ Irene said, getting to the point. ‘And giant Asian hornets.’