Still dressed in the dreamwalker suit, David slid back his door and peered out. The corridor was very dimly lit now. He looked down toward Dishita’s room and noticed the shadows move slightly. Dishita stepped forward into the low light and David went to meet her, his footsteps silent with the soft rubber of his boots. Within moments Petra had joined them, and they all crept over to Adam’s door. Both David and Petra were looking at Dishita expectantly. The older girl gave each of them a small pocket flashlight.

“I suppose I should explain,” she whispered, “but I won’t. All you need to know is that our doors have an emergency release. The codes are simple, and Adam and I amused ourselves by breaking them one afternoon.”

Dishita seemed embarrassed. She turned away and began peeling the adhesive tape off the door, sticking it across the wall for later. When she’d finished, she reached her fingers into a recess in the wall, and a small panel swung silently open. There was a keypad and a narrow screen on it.

“I didn’t know about that,” said Petra. “You mean Security can just get into our rooms?”

Dishita shrugged and started keying in digits. “I don’t know the code for your room, Petra.”

The door hissed open and Dishita slipped into the dark beyond, beckoning the others to follow. Once the door had been closed, Dishita switched on her flashlight. The others did the same.

David saw that Adam’s room was identical to his own, except that someone had clearly lived there for a very long time. It was also obvious that the room had been thoroughly searched. There were clothes and personal stuff everywhere, and a mass of printouts teetered in the center of the desk, beside a laptop on standby. It looked as if someone had been working at the desk very recently, probably an investigator from Security. On one wall was an impressive collection of oriental swords, and on another — quite bizarrely — was a series of photographs of a sinister-looking black cat. Something about it seemed familiar.

“He’s a cat lover?” David had hoped to learn all sorts of interesting things in his enemy’s room, but an interest in small furry animals hadn’t been one of them.

“Oh, that,” said Dishita. “That’s Adam’s little trick. He’s been perfecting it for years. Most dreamwalkers are restricted to their true dreamselves when they dreamwalk, but Adam can change himself entirely. The cat is his favorite. Nasty, sneaky creature. Like Adam himself.”

“You remember he made himself look like you?” said Petra. “To lure Eddie home? Most of us would struggle to do something like that, but Adam was always proud of being a shape-shifter.”

On the floor were two cardboard boxes, shoved to one side as if dismissed. David made a mental note of the cat thing and began to go through them.

“So, what are we looking for?” said Petra.

“Anything interesting,” David replied, not really knowing himself. “Anything that tells us what Adam will do next, I suppose. And anything we can use to stop him.”

“Don’t you think we’re working on that already?” Dishita aimed her flashlight at him, but David didn’t answer. He still felt that all this was intensely personal, and he didn’t trust the man named Roman to do a proper job.

Petra opened the wardrobe and climbed inside. Dishita went to the desk.

“David,” she said, “look at this.”

She was holding a large pile of printed papers. On top was a series of detailed maps showing bomb damage in London during the Blitz, giving precise times and locations.

“See what I mean?” she said. “Adam is very thorough.”

“Okay, but we’ve already saved Eddie from that one. If you find a piece of paper marked Plan B, I’d like to see it.”

David turned back to his cardboard box. It contained a surprising number of books, some of them pretty old, just carelessly tossed inside. And they all appeared to be about ghost sightings and haunted houses.

“Why would he have all these?”

Petra came out of the wardrobe.

“Ah, they’re nothing,” she said with a grin. “We all read those.”

“But why?” said David.

“Why do you think? In case we’re in them. You know, being spotted by Victorian chambermaids in the library at midnight, or floating down castle stairways. We try hard not to be noticed but it still happens. I was once seen rising up through a kitchen floor in Renaissance Venice. I’ve never heard so much screaming! It’s probably in one of these books, actually …”

“We can’t stay here long,” Dishita snapped. “Petra, you can show off your scrapbook later.”

Petra grinned at David and then began looking under the bed.

“I bet the best stuff’s under here.”

David looked around. Where else could they look? Then he remembered the Showing Glass.

“Can’t we find out what he’s been looking at on this?” he said, raising his hand to activate it.

“Don’t!” cried Dishita, pulling his hand away. “If you switch it on, you’ll alert Misty. We’re not supposed to be here, remember? Besides, he would hardly keep anything secret on there.”

David thought about this and was surprised that it reminded him of his mother, of all people. She owned a secondhand bookshop and café, and he was used to seeing tattered old books piled up at home, as well as hearing her low opinion of computers. He grinned when he thought what she’d say if she saw the Showing Glass or heard Misty. He had a sudden pang of homesickness and wondered again what his mum must really be thinking about his disappearance. David turned back to the books, something she had once said to him very clear in his mind.

“Talking of secrets,” he said, “what’s the best way to keep a secret in the Internet age?”

Dishita gave him an impatient look.

“No, seriously,” he said. “How do you keep a secret from a computer hacker? Easy — you write it on a piece of paper.”

David emptied the books out of the box and onto the bed. There were ten in all. Every title was on some ghostly theme, but one of them caught his eye: Ghosts and Hauntings through the Ages. At least, that was what it said on the dust wrapper. But the dust wrapper, as his mum would certainly have pointed out, was ever so slightly too big. He took it off to reveal the true title hidden on the book itself: The Real Railway Children: The Story of London’s Evacuees.

“This one’s got nothing to do with ghosts,” said David. Petra and Dishita came over to look. “It is about Eddie’s time, though. But why would Adam be reading about kids and trains?”

David thought of his mum again and balanced the book on his hand, spine down. It fell open at a place that had obviously been looked at a lot. David closed the book and then let it fall open again. The same thing happened.

The double page that lay open before him contained a single large black-and-white photo. It showed a railway station with swarms of children in coats, scarves, and caps, grouping up around a train shrouded in steam: evacuees from the Blitz, with boxed gas masks around their necks and blank faces that stared into an unknown future without their parents. It was like so many pictures David had seen in history lessons at school, but as he looked at it he had a sudden idea and began scanning the faces closely, wishing there was more light.

“Oh, give that to me,” Dishita said. She snatched the book and lit it with a steady beam. After a moment she gasped and held the book out to David, tapping the photo with a long, red fingernail.

“Who is this, David?”

He looked into the photo, and his breath caught in his throat. Among the anxious faces and steam clouds was someone he knew.

It was Eddie.

He grabbed the book back.

“There’s no date,” he said. “So maybe …”

“Maybe nothing!” Dishita pointed again. “Look at him closely.”

David peered into the photo and, despite the coarse grain, he could see that Eddie’s hair was wild and his face marked with burns. The coat he was wearing looked far too big for him.

“In the original time line, Eddie and his mother left the city by train the day after their home was destroyed,” said Dishita, speaking quickly. “They went from Paddington station. Obviously we’ve been back to watch that train — it was one of the first places we visited when your grandfather went missing — but Eddie wasn’t there. The station was so crowded we had to give up, and anyway, history had changed, making the Archive unreliable. But this picture proves that he did go to the station at some point shortly after the fire. All we have to do is find out exactly where and when this photograph was taken, and we’ll have him.”

“But …” David blinked at Dishita. “… but how can Adam have this? I mean, how can Adam have seen Eddie in this picture before he’d done anything to change his history? It doesn’t make sense.”

“Oh, when will you take that training program, David? In the world of time-travel, common sense gets turned on its head. This photo is what we call a foreshadow. Sometimes, when someone in the present has absolutely made up their mind to change the past, tiny traces of the consequences of that change can already be detected in history, even before the change is made. This is one of the reasons we often get ahead of the Haunting. No wonder Adam tried to hide it. I just don’t understand why Misty didn’t pick up on it, because technically …”

But David had stopped listening.

In his head was a vision of Eddie, walking along the edge of a platform, lost and alone. In the shadows of a nearby railway arch Adam was watching. Beside him crouched the faceless figure of some heartless killer, willing to do Adam’s bidding out of fear or greed. A train was approaching the platform. Eddie stopped to watch it pass, unaware of the movement behind him. All it would take was one quick shove …

David caught sight of his own reflection in the dark of Adam’s Showing Glass. For a moment, as the flashlight beams moved, he saw himself fade away, just as he would surely do if Adam killed his grandfather. And now it seemed that Adam had succeeded where David had failed: He’d found Eddie. In the Showing Glass there was only blackness now.

David began to panic.

“Why are we still standing here?” he cried. “We’ve got to tell the professor!”

Petra put her hand out to him and was about to say something when the door flew open. Four security men barreled straight in, short batons in their hands. Behind them, filling the entrance, loomed the massive figure of Roman.