And there was another reason to feel miserable. It was now early on Friday morning, and Banks could see his planned weekend with Michelle Hart quickly slipping away. If, indeed, the fire had been deliberately set, and if two people had been killed, then it would mean canceled leave and overtime all around. He’d have to ring Michelle. At least she would understand. She was used to the vagaries of the police life, being a DI with the Cambridgeshire Constabulary, still living and working in Peterborough despite the controversial outcome of the case she and Banks had worked on there the previous summer.

PC Smythe came back with a vacuum flask and four plastic cups. It was instant coffee, and weak at that, but at least it was still hot, and the steam that rose when Smythe poured it helped dispel some of the dawn’s chill. Banks took a silver hip flask from his pocket – a birthday present from his father – and offered it around. Only he and Annie indulged. The flask was full of Laphroaig, and although Banks knew what a terrible waste of fine single malt it was to tip it into a plastic cup of watery Nescafé, the occasion seemed to demand it. As it happened, the wee nip improved the coffee enough to make the sacrifice worthwhile.

“Take the cuffs off him, would you?” Banks asked Smythe.

“But sir…”

“Just do it. He’s not going anywhere, are you, Mark?”

Mark said nothing. After Smythe had removed the handcuffs, Mark rubbed his wrists and clasped both hands around the cup of coffee, as if its warmth were sustaining him.

“How old are you, Mark?” Banks asked.

“Twenty-one.” Mark pulled a dented packet of Embassy Regal out of his pocket and lit one with a disposable lighter, sucking the smoke in deeply. Seeing him do that made Banks realize they would have to have the boy’s hands and clothing checked for any signs of accelerant as soon as possible. Such traces didn’t last forever.

“Now, look, Mark,” said Banks, “what you have to realize first of all is that you’re the closest we have to a suspect for this fire. You were hanging about the scene like a textbook arsonist. You’re going to have to give us some explanation of what you’re doing here, and why you ran when we approached you. You can either do it here and now, without the handcuffs, or you can do it in a formal interview at Eastvale nick and spend the night in a cell. Your choice.”

“At least a cell would be warm,” Mark said. “I’ve nowhere else to go.”

“Where do you live?”

Mark paused for a moment, tears in his eyes, then pointed a shaking hand toward the northernmost barge. “There,” he said.

Banks looked at the smoking remains. “You lived on that barge?”

Mark nodded, then whispered something Banks couldn’t catch.

“What?” Banks asked, remembering that the firefighters had found a body on that barge. “What is it? Do you know something?”

“Tina… Did she get off? I haven’t seen her.”

“Is that why you were hiding?”

“I was watching for Tina. That’s what I was doing. Did they get her off?”

“Did Tina live with you on the barge?”

“Yes.”

“Was there anyone else?”

Mark’s eyes burned with shame. “Yes,” he said. “That’s where I was. A girl. In Eastvale. Tina and I had a row.”

That wasn’t what Banks had meant, but he absorbed the unsolicited information about Mark’s infidelity. That would be a tough one to live with; you’re screwing another woman and your wife, or girlfriend, burns to death in a fire. If, that is, Mark hadn’t set it himself before he left. Banks knew that Tina’s was probably one of the two bodies the firefighters had found, but he couldn’t be certain, and he was damned if he was going to tell Mark that Tina was dead before finding out what he’d been doing when the fire broke out, and before verifying the identity of the bodies.

“I meant, was there anyone else living with you on the barge?”

“Just me and Tina.”

“And you haven’t see her?”

Mark shook his head and rubbed his nose with the back of his hand.

“How long had you lived there?”

“About three months.”

“Where were you tonight, Mark?”

“I told you. I was with someone else.”

“We’ll need her name and address.”

“Mandy. I don’t know her last name. She lives in Eastvale.” He gave an address and Annie wrote it down.

“What time did you get there?”

“I got to the pub where she works – the George and Dragon, near the college – a bit before closing time. About quarter to eleven. Then we went back to her flat.”

“How did you get to Eastvale? Do you have a car?”

“You must be joking. There’s a late bus you can catch up on the road. It leaves at half past ten.”

If Mark was telling the truth – and his alibi would have to be carefully checked with the bus driver and the girlfriend – then he couldn’t possibly have started the fire. If it had been set before half past ten, there would have been nothing left of the barges by half past one, when Andrew Hurst reported the blaze. “When did you get back here?” Banks asked.

“I don’t know. I don’t have a watch.”

Banks glanced at his wrist. He was telling the truth. “How late? Twelve? One? Two?”

“Later. I left Mandy’s place at about three o’clock, by her alarm clock.”

“How did you get back? Surely there are no buses running that late?”

“I walked.”

“Why didn’t you stay the night?”

“I got worried. About Tina. Afterward, you know, sometimes things start to go around in your mind, not always good things. I couldn’t sleep. I felt bad. Guilty. I should never have left her.”

“How long did it take you to get back here?”

“Maybe an hour or so. A bit less. I couldn’t believe the scene. All those people. I hid in the woods and watched until you found me.”

“That was a long time.”

“I wasn’t keeping track.”

“Did you see anyone else in the woods?”

“Only the firemen.”

“Mark, I know this is hard for you right now,” Banks went on, “but do you know anything about the people on the other barge? We need all the information we can get.”

“There’s just the one bloke.”

“What’s his name?”

“Tom.”

“Tom what?”

“Just Tom.”

“How long has he been living there?”

“Dunno. He was there when me and Tina came.”

“What does he do?”

“No idea. He doesn’t go out much, keeps himself to himself.”

“Do you know if he was home last night?”

“I don’t know. It’s likely, though. Like I said, he hardly ever went out.”

“Seen any strangers hanging about?”

“No.”

“Any threats made?”

“Only by British Waterways.”

“Come again?”

Mark gave Banks a defiant look. “You must have worked out that we’re not your typical middle-class folk.” He gestured to the burned boats. “Those were clapped-out hulks, hadn’t been anywhere in years, just sitting there, rotting away. Nobody knows who owns them, so we just moved in.” Mark glanced at the barge again. Tears came to his eyes and he gave his head a little shake.

Banks allowed him a moment to collect himself before continuing. “Are you saying you’re squatters?”

Mark wiped his eyes with the backs of his hands. “That’s right. And British Waterways have been trying to get rid of us for weeks.”

“Was Tom squatting, too?”

“Dunno. I suppose so.”

“Was there any electricity on the boats?”

“That’s a laugh.”

“What did you do for heat and light?”

“Candles. And we had an old woodstove for heat. It was in pretty bad shape, but I managed to get it working.”

“What about Tom?”

“Same, I suppose. They were both the same kind of barge, anyway, even if he had done his up a bit, slap of paint here and there.”

Banks looked back at the burned-out barges. An accident with the stove was certainly one possible explanation of the fire. Or Tom might have been using a dangerous heating fuel – paraffin, diesel or Coleman fuel, for example. But all that was mere speculation until Geoff Hamilton and the pathologist had done their jobs. Patience, Banks told himself.