Somehow, along with learning how to fight, how to be angry with other people – and how much you liked it – went learning to dress yourself, discovering which clothes suited you, developing an eye for Spanish embroidery and Valenciennes lace. Perhaps Robin was right. Perhaps the revenge game did require style.

Ellini still had no idea how to move in these flattering fashions. She still slumped her shoulders and dragged her heels. But there was something new inside her, all the same – some kind of boldness that terrified and excited her at the same time.

Tonight, she was wearing an embroidered gown in deep purple that Robin had ordered from the dressmaker's in Petticoat Lane. It was disturbing to find that he knew her exact measurements, but she had partially forgiven him when she'd seen the dress. 

The maids had been in raptures when she'd unwrapped it. 

"Such a generous husband, and with such good taste, madam! What he wouldn't do for you!"

She supposed this meant that he hadn't tried to seduce any of them – or, possibly, had fought off their advances. The thought disturbed her even more.

Ellini added her own touches to the outfit, because she refused to let Robin dress her up like a doll. She put on the black velvet choker that she wore with everything now, because it reminded her of the ribbons she used to twine around her arms on the Oxford rooftops. It was a little piece of the costume, and so it gave her a little piece of the courage, of Charlotte Grey.

She had no idea why Robin was trying to re-make her as an elegant, stylish woman. Was it about owning her? Or getting revenge on Jack? Perhaps he thought they were one and the same.

He was certainly keeping an eye on Jack, in his secretive way. He had the papers delivered directly to him at the breakfast table – and, somehow, the paperboy knew that these precious missives were not supposed to fall into Ellini's hands. She had once met the boy on the stairs and offered to take the papers in to Robin herself, and he had gawped at her for several moments, muttered "Beg pardon, ma'am", and launched past her into the breakfast room.

Ellini knew why this was. The papers had been full of breathless stories about Jack Cade for the past three months. But she was still annoyed at the concealment. If Robin had been paying attention, he would have known that she was just as desperate to avoid stories about Jack as he was desperate to keep them from her.

At any rate, he didn't try to keep the papers from her today. Today, he slapped the Telegraph down on her dressing-table with a triumphant smile and the words "I've found them."

Ellini stared at her own reflection in the mirror, stony and white under the rouge. "Found who?"

"Listen," said Robin, picking the paper up again, and rustling it for effect. "'Alas, it is no uncommon occurrence for our watermen to pull the bodies of dead girls out of the river. Many have been driven to end their lives through the desperation of poverty or the ill-treatment of their neighbours. Many have no friends or family remaining who can offer a shred of evidence as to the motivation behind their crime. And there are some who, like the young woman pulled out of Duckett's Canal on Monday night, become the unwitting instrument of a conspiracy, even after death.'"

"'The young woman who so tragically lost her life in the Canal was identified the following morning by her father, Patrick Riley, a publican from Shoreditch, who had feared that the girl might 'do something desperate', in his words. At the Inquest, he explained to the Coroner that his daughter had been very happy until the previous week, when her fiancé had broken off their engagement, even going so far as to declare – in what he assumed to be some kind of grotesque joke – that he had never met her before in his life.'"

"'When it was discovered that this fiancé was none other than James Whittaker, son of Sir Edmund Whittaker, the Honourable Member of Parliament for Harrogate, the Coroner had the young man sent for without delay.'"

"'James Whittaker was questioned, first by the police, and then by the court's doctors, when it became apparent that he really believed he did not know the girl. He said he had never seen her before the previous week, when she had accosted him in the street, insisting that she was his fiancée. The man was certainly not suffering from amnesia, because he remembered every particular about his own past, except as it related to the drowned girl. When he was presented with letters that he had written to her, he could only declare, with a sincerity and distress which was obvious to everyone present, that they must be forgeries.'"

"'Suspicion then began to fall on the young woman's parents, who could produce no evidence, except for the letters, that Mr Whittaker had ever been acquainted with their daughter at all. The likeliness of their contracting an engagement, when they came from such very different walks of life, was called into question, and Mr Whittaker's lawyer suggested that this might be an attempt to ruin the family reputation, at a time when Sir Edmund Whittaker was campaigning for re-election.'"

"'A verdict of insanity was returned, which at least spared the poor young lady the ignominy of being buried in unconsecrated ground. She was interred at Lavender Hill, and the mystery of her delusions – and her parents' motivation – remains, for the present, undiscovered.'"

Robin put down the paper and watched Ellini's reflection in the mirror. Fortunately, she was inscrutable under the powder.

"He seems like a nice man," he said at last. "Do you still want to give him back his memories? The girl's dead – it's not as though he can apologize. Although perhaps her parents might appreciate an apology..."

"I can't do anything without the blood of the conjuror," said Ellini, carefully side-stepping his question. "This-" she prodded the newspaper, "doesn't bring us any closer to the Wylies."

"Well, we'll talk to him. I know where he lives. He studies at Temple Bar, and lodges in the Strand."

"He won't remember being put under the spell."

"But maybe he'll remember some nice lady giving him a drink? It's worth a try." He licked his lips, and said quietly, "You didn't answer my question. Or maybe you did. If you get the chance, will you give him back his memories?"

"I don't know," said Ellini, putting down the brush and dusting powder off her hands. "The spell can take two forms, and one is more... debilitating than the other. He might only have lost his memories, in which case, he could still probably lead a normal life and never have to know the harm he's caused. But if he's lost his memories and his ability to love, it might be worth restoring one to restore the other."

She knew what Robin wanted to hear. He wanted to hear that she would behave without pity to this man, because it might mean that she would behave without pity towards Jack. He didn't seem able to accept the idea that she never intended to see Jack again. Or maybe he just knew that Jack's resources were too good for anyone to stay hidden from him forever.

"What was done to golden boy?" said Robin, licking his lips again.

"Everything."

"I wish I'd seen it."

She gave him a frosty smile. "Yes, I'm sure you do."

***

The next night, they followed James Whittaker from his lodgings in the Strand. Robin took her arm and rhapsodized about how easy it was to stalk someone if you were with a respectable-looking woman. She was starting to wonder if this was the thinking behind her beautiful new dress.

"A man can be as well-dressed as he pleases, but his presence down a dark alley will always make people uneasy. Nobody's afraid of a middle-class woman."

They kept their distance while James Whittaker walked up Charing Cross Road and into Leicester Square. But there – what with it being a Saturday night – he was almost swallowed up by the crowd. Policemen, street-vendors and well-dressed revellers kept cutting across the space between them and obscuring him from view. But he always bobbed back into sight again, in his respectable hat and coat.

Ellini had never followed a man before – it had always been the other way round – and she was afraid she wasn't very good at it. Every now and then, Robin would elbow her and whisper, "Look somewhere else, for god's sake. There's nothing more likely to make a man turn round than staring avidly at the back of his head."

She looked away, but it wasn't more than a few seconds before her eyes swivelled back again – and it was lucky they did, because something very odd happened to the man at that moment. There was some kind of movement in the air behind him. He stopped still and rubbed the nape of his neck, as if something had just brushed past him.

Robin caught Ellini's arm and pulled her to the left, where they sank into the shadows at the side of the square. But James Whittaker hadn't even looked behind him. He was hastening on so fast that Ellini was afraid they wouldn't be able to catch up.

"What are you doing?" she hissed, as Robin pulled her closer to the crumbling stucco of a tobacco-merchant's. "He's getting away."

"Just keep an eye on him for a second, will you? You're good at that."

He ran his hands over the stucco for a few feet, feigning the unsteadiness of a drunk, and then let out a breath through his teeth and pulled something out of the plasterwork.

Ellini, determined not to give him the satisfaction of seeming impressed, returned her eyes to the young man's fast-disappearing back.

"What is it?"

"A dart," said Robin. There was a pause, and then the sound of spitting. "Tipped with Curare."

"What's that?"

"In the interests of preserving your innocence, let's just say it's a nasty poison and leave it at that."

"Since when did you ever care about preserving my innocence?" said Ellini, still staring at the young man. She could only see the crown of his hat now.

"Just put your hands on your hips and berate me for my drunkenness for a moment." Robin scanned the crowds again, this time at the opposite end of the square. There wasn't much to see, except the solid press of human beings, but he must have known what he was looking for, because, after a while, he said, "There. The woman smoking the cigarette holder. The crowd's too thick to give anyone room to manoeuvre a large blow-pipe, but a small one, disguised as a cigarette-holder, could get about that distance, if you knew what you were doing."

Ellini looked. The woman was fashionably dressed in a brocaded opera cloak, with bouncy curls of red hair protruding from under her hat. Her face was turned towards the far end of the square, and she seemed to be keeping the young man in view.

"Why would she be trying to kill him?" Ellini breathed. "Do you think she was a friend of the dead girl?"

Robin gave a grimacing shrug. "Dressed too expensively to be working-class. She's more likely to be a friend of his."

"But she's trying to kill him!"

"Well? All my friends try to kill me, sooner or later."

Ellini stared at him. "And I suppose you never give them a reason? I suppose it's pure caprice?"

But there was no point. He was determined to be in a good mood tonight. They were pursuing someone in the same situation as Jack. It was like a dress-rehearsal for the revenge he really wanted. So, instead of labouring the point, she mumbled, "We'd better keep him in sight, or we'll lose him."

"No need. We'll just keep her in sight, and she'll take us to him. Besides, it's obvious where he's going. Where is everyone going? What else would you do in Leicester Square on a Saturday night?"

He indicated the towering hulk of the Alhambra in front of them. And it was true that the whole crowd seemed to be stumbling towards it as one entity, albeit an entity that pushed and shoved and scuffled, like a hydra squabbling with its own heads.