They walked into the evil-smelling taproom, a dank, musty place. The windows were boarded and shuttered, a few oil lamps were lit, filling the room with a greasy smell. In their flickering light the customers who sat on overturned casks looked even more like shapes and shadows from a nightmare.

‘Good day everyone!’ Sir John bellowed. ‘And God bless you!’

Athelstan narrowed his eyes. He could make out the wine tuns on the counter, the small glow of the oven, a few beer barrels.

‘Piss off, Jack!’

‘Now that’s no way to talk to an old friend is it? Who’s that? My goodness, it’s one-eyed Isaiah! There are warrants out for you, my lad. An unsolved burglary in the Poultry?’

‘I am as innocent as an angel,’ the voice croaked back.

‘What do you want, Cranston?’

A figure came out of the shadows. Athelstan first thought it was a man but, in the light of one of the oil lamps, he realised that, despite the leather jacket, leggings and boots, it was a woman. Her stained cambric shirt, slightly too small, emphasised her swelling breasts and thick, fat neck. The face was grotesque: the nose split, a long red ugly gash from top to tip while dagger marks criss-crossed her face. A large pearl dangled on a silver chain from one ear lobe.

‘Now, now, Jack, you haven’t come to arrest old Isaiah, have you?’

He took one step back and bowed mockingly.

‘No, Mistress Vulpina, I have not. I wish a few words with you.’

‘Then you’d best come.’

She led them into a far corner of the taproom and up some narrow, rickety stairs. The chamber above was a stark contrast to the evil drinking den below. The windows on one side boasted coloured glass. The walls were painted white and hung with coloured cloths.

The floor was red-tiled, scrubbed clean, and the furniture looked as if it had been bought from a guild carpenter in Cheapside. Flowers grew in small containers and sachets, filled with perfume, were fixed to the wooden beams along the ceiling. Vulpina led them across to a far corner where chairs were neatly arranged round a polished, oval table. A silver salt cellar stood in the centre, shaped in the form of a castle. She offered them wine but Sir John, surprisingly, refused. Vulpina laughed throatily. In the full light Athelstan could see how, in former days, she must have been a beautiful woman. Her eyes were dark brown, large and lustrous even though they shifted restlessly from one place to another. She was unable to meet their gaze but moved about, touching the salt cellar, staring out of the window or pretending to listen to sounds from the taproom below.

‘You haven’t come for one-eyed Isaiah.’ She peered at Athelstan. ‘You are the Dominican?’ Her lips curled in a sneer. I have few priests among my customers.’

‘For ale and beer?’ Athelstan asked.

The sneer on Vulpina’s face faded.

‘What do you sell?’ Athelstan persisted.

Vulpina tugged nervously at a tuft of her cropped dark hair.

‘Everything.’

‘Including poisons?’ Cranston asked.

Vulpina sat back in her chair, hands cradled in her lap, and batted her eyelids.

‘Oh, Sir John,’ she cooed.

‘Don’t play “Hotpot Meg” with me! There’s not a herb that grows, not a potion which can be distilled, unknown to you.’ He gazed up at the ceiling. I wonder where you keep them, eh?’

Cranston got up and walked round the chamber. He stopped to inspect the wooden panelling placed against the far wall.

‘A veritable warren!’ he exclaimed. ‘Eh, Vulpina? When I was a lad, the Mulberry Tree was known for its secret passageways and hideouts. People could come and go in the dead of night and not be noticed. I don’t think it’s changed. Who has visited you recently, Vulpina?’

‘If I told you, Sir John, you’d only blush. Come and sit down. You have no warrant or licence to enter here.’

‘I could get one.’ He came back and lowered himself into the chair. ‘Now that would be a good day’s work, eh, Vulpina? Me and a dozen burly lads from the city. I wonder what we’d find here?’ He pulled across the silver salt cellar. ‘I am sure this once graced a house in Cheapside.’

Vulpina snatched it back.

‘What do you want, Cranston?’

‘I want you to tell me about poisons.’

‘Do you wish to buy one?’

‘Yes.’ Athelstan spoke up. ‘I want you to sell me a poison.’ He paused. ‘Which I can take but will do no harm. However, if I poured it into Sir John’s ale he would be dead within an hour.’

‘Impossible!’ she snorted.

‘You are sure?’

‘Brother, there’s nothing grown under the sun, of a noxious nature, which won’t harm everyone who takes it.’ She shrugged. ‘To be sure, some will affect you more than others: just like ale or wine will render one man sotted before another.’

‘And you know of no such poison?’ Athelstan persisted.

‘If I did, Brother, I would be very interested. Why do you ask?’

‘Hawkmere Manor,’ Sir John said.

The coroner had hit the mark; Vulpina tried to school her features but a shift to her eyes, a flicker of her tongue betrayed her.

‘I’ve heard its name, an old, gloomy place.’

‘It houses French prisoners,’ Sir John explained. ‘One of them was poisoned.’

‘Ah!’ Vulpina smiled, clicking her tongue noisily. ‘So you put the blame on old Vulpina? Sir John, I tell you the truth. I sell potions and philtres to lovelorn ladies, to men who may wish to get rid of a rival. I do not ask them who they are or where they come from. I am an apothecary.’

‘You are a killer! A red-handed assassin!’ He got to his feet and leaned over the table. ‘One day, when I have time and the necessary warrants, I’ll come back here.’ He went to the door. ‘We are going to leave this lovely place.’ He waited until Athelstan joined him. ‘And I don’t want to be followed. No fracas or sudden affray in the streets below. You’ve been no help, Vulpina, and I’ll remember that!’

‘Sir John!’

He walked back into the room.

‘You are here on Gaunt’s orders, aren’t you? You’re his messenger boy.’

‘I’m no one’s boy!’

Vulpina sneered, her head going back. She studied Sir John under half-closed lids. Athelstan repressed a shiver. He did not like this place: the more he stayed, the more certain he became that he was in the presence of real malevolence, that this woman was steeped in evil. He was used to the rapscallions and rogues of Southwark, people like Pig’s Arse and Godbless who stole and thieved because they had to. Vulpina, however, enjoyed the evil she distilled, revelling in the chaos and the sorrow it caused.

‘I’m waiting, Hotpot!’

‘You are Gaunt’s man.’ She clicked her tongue again and lifted her hand. Athelstan noticed that she wore a skin-tight leather gauntlet on her right hand. ‘I can give you a list of customers, Cranston!’ she hissed. ‘They’d include the so called mighty and good who would have little time for your nose-poking and querulous questions and that includes my Lord of Gaunt! Or rather his lovesick knight. What’s his name? Maltravers? I understand he’s the laughing-stock of the city. He’s taken a couple of French ships so he thinks he can slip between the sheets with Lady Angelica Parr, does he?’

‘What are you saying?’ Sir John took a step threateningly forward.

Vulpina lifted a whistle which hung on a silver cord round her neck.

‘Come on, Fat Jack!’ she taunted. ‘One blast from this and we’ll see how you and your priestly friend can cope with my legion of rats from below!’

He drew sword and dagger. Vulpina’s face lost some of its arrogance.

‘Go on!’ he said. ‘Let’s go at it, Vulpina. Heaven or hell, but you will be dead.’

The Queen of Poisons took a deep breath and let it out noisily.

‘Fine, fine, Sir John. I want you out of here and I don’t want your enmity.’ She let the whistle fall. ‘Gaunt’s man has been here.’

‘Maltravers?’

‘The same.’

‘What did he want?’