“And should they still be dirty.”

Stefan narrowed his eyes. “Trace evidence can be microscopic sometimes. You ought to know that. You’d be surprised how little we can work with.”

“I’m sorry,” said Annie. “I don’t mean to be negative. It’s just… I have a feeling we’re not dealing with an amateur here.”

“And we’re not amateurs, either. Besides, we don’t know what we’re dealing with here yet.”

“True enough,” Annie agreed. “I’m just suggesting that he’ll have done his best to cover his tracks, and the longer it takes us to find him…”

“The more tracks he’ll manage to cover. Okay, I’ll grant you that. But it’ll take more than a car wash and a good polishing to get rid of every atom of soil he might have picked up here. Besides, don’t forget, we’ve got the tire impression to go on. There’s an oil stain, too, by the looks of it.” He pointed to another protected area on the lay-by. “We’ll have that back for analysis by the end of the day. It’s certainly beginning to look as if someone parked here recently, and if it wasn’t you or the fire brigade…”

Annie knew that it was neither she nor Banks. They had been concerned to preserve as much of the scene as they could when they arrived, almost by instinct, so they had left their cars farther up the lane and made their way through the woods without benefit of using a marked path. All in all, then, things were looking promising. Even if the evidence that Stefan and his team painstakingly collected didn’t lead them directly to the arsonist, it would come in useful in court when they did find him.

“Any chance it was a Jeep Cherokee?” Annie asked, remembering what Banks had told her Mark said he’d seen. “Or something similar?”

Stefan blinked. “Know something I don’t?”

“Just that something resembling a Jeep Cherokee has been reported seen in the area. Not last night, but recently.”

Stefan looked down at the tire tracks. “Well,” he said, “it’s something to go on. We can certainly compare wheelbase and track width. Anyway,” Stefan said, opening the door of the mobile unit with a flourish, “it’s not exactly the Ritz, but the heater works. How about coming in for a cuppa?”

Annie smiled, her body leaning toward the source of heat the way a sunflower leans toward the sun. “You must be a mind reader,” she said, and followed him in.

By the time Banks and Frances Aspern got to Western Area Headquarters after Mrs. Aspern’s positive identification of Christine at the mortuary of Eastvale General Infirmary, Annie had already left to talk to the SOCOs at the canal. Banks arranged for a uniformed constable to drive Mrs. Aspern back home, and he had just settled down to review the findings so far, with Gil Evans’s Jimi Hendrix orchestrations playing quietly in the background, when Geoff Hamilton appeared at his office door. Banks invited him in and Hamilton sat down, glancing around.

“Cozy,” he said.

“It’ll do,” said Banks. “Tea? Coffee?”

“Coffee, if you’ve got some. Black, plenty of sugar.”

“I’ll ring down.” Banks ordered two black coffees. “Anything new?”

“I’ve just come from the lab,” Hamilton said. “We carried out gas chromatograph tests this afternoon.”

“And?”

Hamilton took two sheets of paper and a videotape from his briefcase and laid them out on Banks’s desk. The sheets of paper looked like graphs, with peaks and valleys. “As you know,” he said, looking at Banks, “I took debris samples from a number of places, especially on boat one, Tom’s boat, the main seat of the fire. I don’t know how much you know about it,” he went on, “but gas chromatography is a relatively simple and quick process. In this case, we put the debris in large cans, heated them and used a syringe to draw off the headspace, the gases given off, and we then injected that into the chromatograph. This” – he pointed to the left graph – “is the chromatogram we got from the point of origin.” He then pointed to the graph beside it, which, to Banks, looked almost identical. Both showed a series of low to medium peaks with one enormous spike in the middle. “And this is the chromatographic representation of turpentine.”

“So we were right,” Banks said, studying the chromatograms. “What about the other boat?”

“Apart from the streamers I noted on my initial examination,” Hamilton said, “there are no other signs of accelerant. Anyway, that’s the physical evidence so far. Turpentine is your primary accelerant. Its ignition temperature is 488 degrees Fahrenheit, which is quite low. As we found no evidence of timing or incendiary devices, I’d say someone used a match.”

“Deliberate, then?”

Hamilton looked around, as if worried that the room was bugged, then he let slip a rare smile. “Just between you and me and these four walls,” he said, “not a shred of doubt.”

The coffee arrived and both remained silent until the PC who delivered it had left the office. Hamilton took a sip and lifted up the videotape. “Want to watch a movie?” he asked.

Videotaped evidence and interviews were so common these days that Banks had a small TV/Video combination in his office. Hamilton slipped the tape in and they both got a driver’s-seat view as the fire engine raced to the scene.

Most engines, or “appliances,” as the firefighters called them, were fitted with a “silent witness,” a video recorder that taped the journey to the source of the call. It could come in useful if you happened to be really quick off the mark and spotted a getaway vehicle, or arrived at the scene and got a picture of the arsonist hanging about enjoying his handiwork. This time, there was nothing. The fire engine passed a couple of cars going the other way, and it would probably be possible to isolate the images and enhance the number plates. But Banks didn’t hold out much hope they would lead anywhere. The fire was well under way by the time Hurst called it in, and the arsonist would be well away, too. It was an exhilarating journey, though, and Hamilton ejected the tape when the appliance came to a halt at the bend in the lane.

“There’s one thing that bothers me,” Banks said. “The boy, Mark, described the artist’s hair as brown but what little of it we saw on the boat was more like red.”

“Fire does that,” said Hamilton.

“Changes hair color?”

“Yes. Sometimes. Gray turns blond, and brown turns red.”

“Interesting,” said Banks. “What about Tina? Could she have survived?”

“If she’d been awake and aware, yes, but the state she was in… not a chance.”

“The way it looks, then,” said Banks, “is that the artist on boat one was the primary victim, yet some small effort had been made to see that the fire spread to boat two, where Mark and Tina lived. But why Mark and Tina?”

“I’m afraid that’s your job to find out, not mine.”

“Just tossing ideas around. Elimination of a witness?”

“Witness to what?”

“If the arsonist was someone who’d visited the victim before, then he might have been seen, or worried he’d been seen.”

“But the young man survived.”

“Yes, and Mark did see two people visit Tom on different occasions. Maybe one of them was the killer, and he had no idea that Mark was out at the time. He probably thought he was getting them both, but he was in a hurry to get away. Which means…”

“What?”

“Never mind,” said Banks. “As you said, it’s my job to find that out. At the moment I feel as if we’ve got nothing but assumptions.”

Hamilton tapped the graphs and stood up. “Not true,” he said. “You’ve got confirmation of accelerant usage in a multi-seated fire.”

Hamilton was right, Banks realized. Until a few minutes ago, all he’d had to go on were appearances and gut instincts, but now he had solid scientific evidence that the fire had been deliberately set.

He looked at his watch and sighed. “Dr. Glendenning’s conducting the postmortem on the male victim soon,” he said. “Want to come?”