“I’m picking up ghosts everywhere,” she said quickly, in self-defence. “I’ve never seen so many hauntings in one place. No actual personality or surviving intent in most of them; only images from the Past, impressed on Time by the extreme conditions of their creation. Snapshots of what was, repeating loops of history, preserved like insects trapped in amber. Presumably drawing energy from our other-dimensional Intruder. Unless they’ve been stirred up by our presence. Or my machines.”

“She doesn’t know what’s going on either,” Happy said to JC, smiling widely.

JC looked at the state of Happy’s pupils and sighed audibly. “Tell me at least you haven’t touched the little yellow pills, Happy. You know what happens when you take the little yellow ones.”

“Not yet,” Happy said cheerfully. “But it’s probably only a matter of time. I always get a bit jumpy when the ghosts start manifesting. In case one of them takes a fancy to me and follows me home like a stray dog. I’m probably the only ghost finder in the Carnacki Institute with his own exorcist on speed dial.”

“I wouldn’t worry,” said Melody. “They’d soon leave, once they got to know you.”

“How very unkind,” said Happy, trying for wounded dignity, then ruining it with a sudden hiccup.

“Never get personally involved with a ghost,” JC said sternly. “No matter how tragic its story. Nothing good can ever come of it.”

“Damn, I’m peckish,” Happy said abruptly. “I’d kill for a curry and chips.”

He wandered over to a nearby vending machine, studied the display of snacks on offer with owlish eyes, and made his selection. He forced money into the slot, then bounced up and down before the machine, humming an old Smiths’ song. The machine chuntered quietly to itself for a while, then a slot opened in the front and the food shot out. Happy actually had the thing half-way to his mouth before he realised something was wrong. He stopped at the last moment, his eyes widened, and his mouth pursed up in disgust as he saw what he was holding. The pastry slip was hot and steaming, but the meat oozing out of it was rotten and decaying. Maggots burst out of the pastry, writhing and roiling. Happy cried out and threw the stinking mess on the floor. It hit with a wet, slapping sound, and Happy stamped on it again and again, making shrill distressed noises, until all the maggots were crushed and dead, and nothing was moving. Then he scraped the bottom of his shoe against the platform and rubbed both hands hard on his jeans.

“Okay, that was interesting,” said Melody. “There’s no way that could have happened naturally.”

“No!” said Happy. “Really? You do amaze me. Of course it didn’t happen naturally! Oh, my comfortable glow is all shot to hell now. My anus has puckered itself all the way up to my chest bone.”

“Far too much information, Happy,” murmured JC.

“There’s no way the food could have decayed that quickly inside the machine, under normal conditions,” said Melody. “Whatever it is that’s down here, it’s draining the living energy out of everything within reach. Presumably our Intruder needs help in maintaining its hold on our dimension.”

“You’re going to try and explain entropy to me again, aren’t you?” said Happy. “Please, JC, don’t let her explain entropy to me again. My head still hurts from the last time.”

“Hush, man,” said JC. “It would seem our Intruder is accumulating power and adjusting local conditions to suit its own needs. But to what end, what purpose? Why does it need a physical presence in our world? What’s it all about?”

“My name is not Alfie,” Happy said sternly.

Melody checked her instrument panels again. “I can tell you this; there’s more than one centre down here, more than one power source. The energy readings are off the scale in a dozen different locations. If I’m interpreting these data correctly . . . we’ve got ghosts, demons, and abhuman creatures swarming all over this station. Drawn here, like moths to a flame . . . or tourists to a disaster site. Something very big, and very bad, is slowly coming into focus here. Once it’s fully manifested in our material plane, it will have established a beachhead, a door between its dimension and ours . . . one we might not be able to force shut again. In which case, the haunting would spread, and the whole of London would get hit by the psychic fall-out.”

“Damn,” said JC. “And I thought Happy was the gloomy one.”

“And,” said Melody, “I’m pretty sure . . . we’re not the only living people down here. Someone else is down here with us.”

Whereas the Carnacki Institute is concerned with gathering knowledge of the unseen world in order to protect Humanity, the Crowley Project doesn’t give a damn. All they care about is amassing knowledge and power for the sake of the Project. They only investigate hauntings so they can take advantage of the situation and exploit it for their own ends. Some say they want to rule the world, and some say they already do. The Crowley Project loot and brutalise all the manifestations of the unseen world because they want to know the secrets of Life and Death. They want to rule not only this world but the afterworlds, too. They want it all.

Some of them eat ghosts, consuming their energies and absorbing their knowledge and memories. Some of them create bad places on purpose, poisoning the psychic wells of the world with awful technologies and bad intent, dropping bloody bait into the waters to attract otherworldly monsters. For the fun of it, and the sport. They create disasters and glory in destruction, and dance in the aisles of crashing planes. Just because they can. Do what thou wilt is the whole of their law. They are the main rivals and deadly enemies of the Carnacki Institute, and so it has been for centuries. Because the Light must always be at war with the Dark, or because Good and Evil simply cannot abide each other; or maybe because every coin must have two sides. Two organisations, forever at each other’s throats; two small fish in a pond that is so much bigger than either of them have ever realised.

Field agents Natasha Chang and Erik Grossman have come to Oxford Circus Tube Station on behalf of the Crowley Project. And they’re not there for the ghosts.

Natasha Chang was a self-made femme fatale, her bright eyes and merry smile a cover for a cutting edge and a concealed agenda. A beautiful creature in her late twenties, she had artfully bobbed dark hair, dark, slanted eyes, and an even darker heart. Daddy was a corrupt Hong Kong businessman with a thing for the English aristocracy, who fled Hong Kong in a hurry, one step ahead of the police and all the people he’d cheated and betrayed. He brought his considerable fortune to the United Kingdom and married a very minor member of a very old family, who needed the money. Daughter Natasha grew up half-Chinese, half-English rose, privileged and cosseted but still looked down on as a half-breed by all her peers at school. She emerged from that venerable institution driven to win at any cost. The coldly ruthless child of cold and ruthless parents, Natasha struck out for freedom and an independent income at an early age. By helping Mummy murder Daddy when she was fourteen years old. She could have spent the rest of her life partying, pampering and indulging herself; but that wasn’t enough for Natasha. There were slights to be avenged. She ached to be out in the world, doing things. Bad things, preferably. Because every femme fatale needs more-and-more-difficult objectives to test herself against, to reassure herself that no-one runs her life but her.

Natasha cultivated an arrogant aristocratic poise that never failed to fascinate and intimidate those around her, and she strode through the world as though she fully intended to walk right over anyone who didn’t get out of her way fast enough. A lot of men found that attractive, and a challenge, as they were supposed to, the fools. Natasha’s mixed-race background gave her an exotic air that she exploited mercilessly in affairs of the heart. She’d been married three times and widowed four. (That last one took a lot of killing.) She wore the very best clothes by the very best designers and never looked less than stunning. Because for Natasha, her beauty was another weapon she could use. Currently, her make-up was bold and striking, with subtle Egyptian touches around the eyes; her long, sharp fingernails were painted with real gold leaf; and she wore enough heavy rings on both hands for them to qualify as knuckle-dusters. She was wearing a pink leather cat suit, her favourite, because she had seen Eleanor Bron wear one in the Beatles movie Help! at an impressionable age.