Bolt thanked him and walked out with the map before his boss had a chance to change his mind. It was still a case of searching for a needle in a haystack, but at least the haystack was getting smaller.

And any effort was worth it if it led to Tina.

The interior of the lorry's cab still reeked of death, even though they'd removed the driver's body more than an hour earlier, and Eamon Donald was pleased when he'd finished drilling the holes through to the back that were needed for the bomb's wires, and could finally get out into the comparative fresh air for a much-needed smoke. He'd been trying to give up for the best part of a decade now, a process that had started when his old man, a lifelong smoker, contracted terminal lung cancer, but he'd never managed to last for more than a week, and for the time being at least he'd given up giving up.

He lit a Marlboro Light and approached Stone and O'Toole, both of whom were hard at work among the pieces of drainpiping Stone had been sawing up earlier. O'Toole was using a large measuring jug to fill up each tube with a ready-made explosive slurry mix of ammonium nitrate and fuel oil that he was getting from a barrel next to him, while Stone was on his hands and knees attaching handfuls of six-inch nails to the tube exteriors using thick rolls of industrial masking tape. Every ingredient they were using could be bought legally by people who knew what they were doing.

'How's it going, lads?' Donald called out, making sure he stood well back from them with the cigarette.

'Another hour, I reckon,' answered O'Toole. 'Then we're going to need a break.'

Stone grunted something that sounded like agreement.

'And when you're done you can have one, don't worry.'

Donald looked at his watch. It had just turned half past twelve and they were well ahead of schedule. He was also beginning to get hungry, and hoped that Hook had got in some supplies. Donald liked his food, and he'd always found it difficult to function on an empty stomach. Somehow, though, he knew Hook wouldn't have anything tasty on offer. He wasn't the kind to get pleasure from eating. He wasn't really the type to get pleasure from anything bar, it seemed, rape and murder.

As he thought these unkind thoughts about his current employer, the barn doors opened and Hook appeared in his Friday the 13th-style boiler suit and gloves, his anaemic face looking like something out of a 'plastic surgery gone wrong' documentary. Donald wondered how the guy ever managed to blend into a crowd, as he was reputed to be able to do. To him, Hook blended in like a go-go dancer in a nunnery.

As Donald took a long, much-needed pull on the cigarette, Hook came over and guided him towards the front of the lorry, well away from Stone and O'Toole, and out of earshot.

'How's it coming along?' he asked.

'We're doing fine. Your bomb'll be ready on time.'

Hook nodded. 'Good. That's what I want to hear.' But there was something tense about him. He wrinkled his nose, glancing at the cigarette, and Donald remembered that he didn't like smoking.

Tough titty. He took another drag, savouring the taste.

They stopped at the cab, and Hook fixed him with a probing stare. 'I hear that when mustard gas ignites it loses its effect. How are you intending to fix that?'

'Ah, I see you've done your homework.'

'I always do my homework, Eamon.'

'Well, it's very simple really,' he said, unable to mask the enthusiasm he always felt when talking about bombs. 'When those two over there have finished filling the tubes with explosive mix, I'm going to put a detonator in each one and run them through the gaps in the pallets holding the gas. By my calculation there should be two tubes for each pallet. Then we wire them up to a connector box, which is basically the bridge between the explosive-filled tubes and the main detonator in the cab. When we set off the main detonator, the connector box will send a signal through the wiring and our thirty-two mini bombs will explode simultaneously, sending the nails attached to the outside of the tubing flying everywhere, and with enough force to puncture all the cylinders.

'But' – and here Donald paused for effect, feeling especially pleased with himself – 'the beauty of the design is that, because the tubes are made from toughened plastic, the power of the blast will be contained within each tube itself – think of it like a blanket smothering the flames – so the cylinders will get peppered with holes and thrown all over the place, but the gas itself won't get ignited. We might lose a couple, because it's not entirely foolproof, and a few won't get punctured, but I'm reckoning that ninety-five per cent of the cargo will be released into the surrounding air undamaged. With a little bit of a breeze and no rain, everyone in a mile radius will be breathing in pure poison. It'll be the most lethal terrorist attack in UK history. The Brits won't know what fucking hit them.'

'And you've put in the modifications we talked about?' asked Hook quietly.

When he'd hired Donald, Hook had stipulated that the bomb had to explode no matter what, even if the lorry was intercepted by the security forces, otherwise none of them would get their money. Technically speaking, this wasn't a problem at all, as Donald had explained. All it required was a pressure pad placed under the driver's seat connected to the bomb's battery pack. Once the bomb was live – and it could be made live with the flick of a switch before the lorry had even begun its journey – then the moment the driver lifted his weight from the seat, the movement from the pressure pad would set off the bomb, so even if he was shot dead while driving and toppled over, it would still explode. It was a tactic used by terrorist groups with vehicle bombs across the Middle East to ensure that, even if their suicide bombers experienced a sudden loss of nerve, their deadly cargoes would still detonate.

There was only one problem. When Donald had agreed to do the job, he hadn't realized that the driver was going to be a volunteer from the old days.

'They'll be put in before the end,' he answered. 'It's only a five-minute job. But does it have to be O'Toole who drives? He's one of our people. Why not use Stone? He's nothing to us.'

Hook stared at him blankly. 'Stone's too stupid. We need someone reliable. It's going to be O'Toole.'

Donald dragged hard on his cigarette, looking over Hook's shoulder to where O'Toole and Stone were working away. O'Toole would never suspect that his old comrades would betray him, and the fact that the man who'd hired him couldn't give a shit pissed Donald off.

'You never really believed, did you, Michael?' he said rhetorically, using the other man's real Christian name. 'In any of what we were doing.'

'That's none of your business.'

'You know, what I can't understand is why you're doing this. I'm doing it because I hate the Brits. Because I owe them for four hundred years of oppression, and because they never baulked at killing innocents, so why the hell should I? But what do you get out of this? I mean, I know your client, whoever he is, is bound to be paying you a lot of money, but it strikes me that a man like you has already got plenty of cash, and this kind of job, leaving so many dead and every cop in the country hunting you down… No amount of money's worth that.' He took a last drag on his cigarette and crushed it underfoot. 'So, what's your motivation?'

Hook leaned forward and his whole face seemed to darken. 'Because I fucking can,' he hissed, eyes sparkling maliciously. 'Now, do me a big favour, Eamon Donald, and get back to work.'

The two men eyeballed each other for several seconds, but it was Donald who backed down and turned away, immediately regretting that he'd seen fit to rile the other man. Regretting, too, that he'd ever agreed to work with him in a freelance capacity. The pay was good – a hundred and fifty grand, fifty already in his hands, the other hundred following as soon as the job was finished. But for the first time he wondered if he was going to actually receive this last instalment. If Hook was prepared to leave O'Toole dead, why not Donald himself as well?