“Something new has come to Oxford Circus,” it said. “Or something very old. Something from the afterworlds has manifested in the tunnels, deep down in the dark. And it’s not alone, down there. Its mere presence is enough to stir up ghosts and demons and monsters. The darkness is alive. And it’s hungry.”

Erik looked at Natasha. “See? I told you!”

“Shut up. We already knew there was a powerful force loose in the station.”

“Still, something from the afterworlds, made flesh and therefore vulnerable . . .” Erik rubbed his hands gleefully. “Now that’s a prize worth having.”

“It’s cold, and it burns,” said the cat head. “It’s wild and fierce and free, and it will kill you.”

“You wish,” said Erik absently, and turned off the cube. The cat’s head fell silent, but its unblinking eyes still burned with hate.

“I’m hungry,” said Natasha.

“Eat your chicken legs,” said Erik.

“Hungry for ghosts,” said Natasha. “There’s nothing quite like them, nothing so . . . satisfying. I might even leave a few for you, this time.”

“You know I don’t indulge,” Erik said primly. “Nasty habit, and dangerous to your mental health. If you ever had any.”

“Prude,” said Natasha. “Scaredy-cat.”

Erik sniffed loudly but wouldn’t meet her eyes. “I value the integrity of my mind far too much to risk contaminating it with inferior thoughts and memories.” He gave in to curiosity and looked almost defiantly at Natasha. “I simply do not see what you people get out of it. Don’t you ever get . . . confused, with other people’s memories and identities suddenly crashing about inside your head?”

“Darling,” said Natasha, “that’s the good part. That’s the rush. That’s what makes them so very tasty.”

“You’re disgusting.”

“I know you are, but what am I?”

And then they broke off and looked around sharply, as every ticket machine in the lobby suddenly spat up all the coins it had taken. Pound coins and assorted change jumped and clattered across the floor as they were ejected with force, bouncing and rolling everywhere, shining and shimmering in the over-bright light. Some of them rolled right up to Erik’s feet, and he reached down to grab a handful; but Natasha stopped him with a harsh command. One by one the machines ran out of money and fell silent. Coins lay scattered all over the floor. Natasha watched the ticket machines carefully for a while, to see if they’d do anything else, but they remained still and silent. She turned her back on them and the money with studied insolence and returned to the top of the escalator. Erik carefully packed his cat-head computer back into its pack, then casually scooped up a handy two-pound coin. Only to yell and throw it away again.

“Hot!” he said. “Hot hot hot!”

“Did it burn you?” said Natasha, not looking around.

“Yes!”

“Good.”

Erik scowled. “Damned thing was hot enough to have been coughed up from Hell itself. What was that for?”

“Someone is playing games with us,” said Natasha.

“Could it be JC and his people?” said Erik, immediately forgetting the pain in his fingertips. “Could they know we’re here?”

“No,” said Natasha. “I’d know . . . if they knew. I think this is something else . . .”

She left the elevators, made her way back through the open ticket barriers, and strolled unhurriedly around the entrance lobby, frowning as she forced her telepathy into every psychic nook and cranny. Her gaze shot suddenly to one side, and she advanced remorselessly on one corner. And then she stopped as Erik hissed her name, and a ragged man appeared suddenly in the lobby with them. He shuffled slowly around, ignoring the coins on the floor as though they weren’t there, and perhaps for him they weren’t. He looked like one of the homeless, tall but stooped, a ragged man in ragged clothes, wrapped up in a long coat stained with damp and mould. He had long, matted hair and a filthy beard, and his eyes were dull, preoccupied with cold and hunger and memories that wouldn’t go away. He slowly made a full circle of the lobby, shuffling right past Natasha and Erik without even seeing them. Until, slowly, he seemed to become aware that he was not alone. His head came up, and his dull eyes fixed on Natasha. He didn’t seem at all surprised to see her, or even to care that much. He held out one filthy hand, mutely asking for money.

“He’s not real,” said Erik. “He’s a ghost.”

“Thank you, I had worked that out for myself,” said Natasha.

“Is he aware?” said Erik, professionally interested. “Or is this only a stone tape, a psychic recording?”

“Oh no,” said Natasha. “There’s still some of him here. I can pick up some of his thoughts, rattling around inside his head. He had a name once, and a family and a job; but he lost them all. He ended up on the streets, begging for small change, but he was never very good at it. He died here, in that corner, locked in overnight and overlooked by everyone. Would you like to know his name?”

“No,” said Erik. “It doesn’t matter. He doesn’t matter. This is a simple haunting, stirred up by our presence, or perhaps the workings of my little computer. He isn’t what we’re here for.”

“Hush,” said Natasha. “I told you I was hungry.”

She advanced slowly on the homeless ghost, which stood there, staring at her dully like an animal that had been beaten into submission. It wasn’t until she was right before him that he seemed to become aware of the danger he was in. He looked at Natasha with growing horror but couldn’t seem to move. Natasha licked her lips.

“You don’t even know you’re dead, do you? How . . . delicious.”

She locked his gaze with hers, reaching out with her mind, forcing him to see her clearly through sheer force of will. The ghost’s face twisted with horror, and he began to howl, a wordless scream of helpless dread. The cry of someone who knows no-one will come to save him. The ghost could see Natasha for what she was; and it terrified him. He drifted slowly backwards, not even moving his feet, and Natasha went after him. She stalked him all around the lobby, for the fun of it.

Until, finally, she lunged forward and locked her mouth on his, blocking off his howl. Living lips clamped down on a dead mouth, and he hung helpless before her as she sucked him dry, eating up every last trace of energy and consciousness that remained to him, and savouring it all. Bit by bit he faded away, becoming increasingly insubstantial as there was less and less of him, until not even a trace of the ghost remained. Natasha straightened up, licked her lips slowly, and laughed almost drunkenly. She looked sideways at Erik, backed up against the far wall, and sniggered at him.

“You don’t know what you’re missing, little man. You must learn to develop a taste for the good things in life. Ooh . . . I’m Daddy’s bad little girl . . . Such a little terror. Are you excited, Erik? Did that turn you on? It did, didn’t it? You’d love me to do that to you, wouldn’t you, Erik? And maybe one day, I will. But I guarantee you won’t like it one little bit.”