She had no idea how much time passed. It could have been fifteen minutes. It could have been half an hour. During that time she saw two other men – one immense with a shaven head, the other in his fifties with grey hair – go in and out the back of the lorry. They were carrying what looked like shorn-off drainpiping, tubes that were sealed at either end and filled with something heavy enough that it took two of them just to carry one of them. She wondered what it was they were doing, and what it might have to do with the kidnapping and murder of Jenny Brakspear, but they worked in silence, giving her no clues.

Finally, just as Tina was beginning to despair, the moustachioed guy in the cab shouted something she couldn't make out to the two in the rear, then jumped down, leaving the door open, and walked towards the back of the lorry. Tina pulled the door open a little further and saw the other two men get out the back, and then the three of them went out of view. Opening it still further, she saw them disappear through a door at the end of the barn.

This was it. Her one and only chance. She didn't hesitate, hopping across the floor in the direction of the front of the lorry, hoping she could use it as cover to get to the main doors, and freedom. The effort made her feel faint but she also felt a desperate elation at the thought that she might make it.

She was already promising herself a bottle of decent Rioja and a good smoke as reward for her pains when she heard harsh laughter and saw that they were coming back into the barn.

She was only half a yard from the driver's side door as they emerged. Knowing that the second one of the men looked her way she was finished, she toppled forward, grabbed the driver's seat for leverage and heaved herself up into the cab with all the strength she could muster.

It didn't sound like anyone had heard or seen her. There was more laughter, and someone said 'Cheers' in a hard Northern Irish accent similar to her kidnapper's. Tina was panting with the effort, her last reserves of energy seeping out of her, yet she knew she couldn't stay lying across the front seats of the cab. She had to get somewhere out of sight, in case the bald man with the moustache came back.

Biting her lip hard so she didn't cry out in pain, she crawled into the small rest area behind the front seats where the driver slept. There was an old duvet crumpled up on the dirty mattress, and she pulled it over her, lying as still as possible, her heart thumping in her chest.

Only five metres from freedom, but at that moment it might as well have been a thousand miles.

'So you're saying this has something to do with Sir Henry Portman?' Big Barry Freud asked, sounding as shocked as Bolt had felt when he'd seen the photo fifteen minutes earlier.

'It's too big a coincidence otherwise,' Bolt answered, leaning against one of the patrol cars, looking over at Dominic Moynihan's front door where a uniformed officer was rolling out more bright yellow scene-of-crime tape. 'We're going to need to bring him in, find out what he knows.'

'On what charge? So far, all we've got against him is he appears in a photo in a dead man's house.'

'Then we should at least put him under surveillance.'

'Sorry, old mate, but right now we're stretched to the limit. With everything that's going on, I doubt if there's a spare surveillance team this side of Hadrian's Wall.'

Bolt felt his frustration growing. 'Well we'd better find one or all we're going to be left with is more dead bodies and a missing killer who's got away from us again.'

'How did he get away? The Mazda's still there, isn't it?'

'It is. He must have cottoned on to the fact that we were on to him and got himself some other form of transport.'

'Or he's still there somewhere,' said Big Barry. 'We've got people flooding the area, and they're setting up roadblocks on slip roads off the M11.'

Bolt thought this sounded a lot like shutting the stable door after the horse had bolted, but didn't think it was worth pressing the point. Instead, he concentrated on another issue that had been concerning him. 'What I want to know is how come we only picked up the Mazda at junction six. It must have come up on a camera somewhere before that.'

Big Barry sighed. 'It was picked up on the A120 near Stanstead airport twenty minutes earlier, but whoever was meant to be watching for it didn't react quick enough.'

'Shit.'

'My sentiments exactly. But there's nothing we can do about that now.'

'What about the lorry itself? Are we any closer to IDing it?'

'Not yet. Some CCTV images of a possible vehicle have been sent to the FSS for analysis, but we haven't heard anything back yet.'

'At least we know that Hook's been using the blue Mazda, and it was parked overnight in the area the ANPR narrowed it down to, which confirms he's got a base up there somewhere. Since the gas hasn't been released yet, my guess is the lorry will be up there too.'

'It's still too big an area to be of any use to us, Mike,' said Barry. 'We're talking about close to two hundred square miles of north Essex countryside.'

'I've still got Obanje checking through rental properties in the area, but the last time I spoke to him he was snowed under. Can you get him some help?'

'I'll see whether I can move some of your team on to it. What are you going to do?'

'I want to drive up there so that I can be on the spot quickly if we do ID a rental place that looks suspicious.'

'It sounds like it could be a wild goose chase. I could use you back here, old mate.'

But Bolt insisted, knowing that he'd done enough in the past twenty-four hours to warrant being cut some slack by his boss. He also knew he'd be of little use back at HQ, where in effect he'd be sitting round and waiting. He might also be of little use heading up into rural Essex, but at least he'd feel like he was doing something. At that moment he had a desperate urge just to drive.

Big Barry didn't force the issue, so Bolt called Obanje, who'd told him that five of the nine properties whose tenants he'd been checking out in detail were definitely kosher rentals, and he was still trying to find out about the other four. Bolt gave him the good news that he'd now be getting help on his task and wrote down the four addresses still to be confirmed as kosher and rung off.

Mo Khan was making his own mobile phone call a few yards away. He ended it and walked over, unable to completely hide the anxiety on his face. 'I've just been speaking to Saira,' he said wearily.

'How is she?'

'Still blissfully ignorant. Unlike me. I don't know what to do, boss. If anything happened and I could have done something about it…'

'Are she and the kids at home?'

'Yeah, they're all there. My mother-in-law's over at the moment.'

Bolt put an arm round his friend's shoulders and looked him in the eye. 'I know how you feel, Mo, I honestly do. But right now, I think home is the best place for them.'

Mo nodded. 'Yeah, you're probably right. I just wish we had a better idea of who or what they're targeting. Is there any news from HQ?'

'Nothing yet. But I've got the addresses of four suspicious rental properties in the area where the blue Mazda was last night. It's possible one of them could be the one we're looking for. Let's go and check them out.'

Mo didn't look convinced, but he didn't say anything as they walked back to the car.

It had just turned ten past six in the evening. The gas had been in the country for just over twelve hours.