Steven relaxed a little and sipped his own coffee. ‘I can’t promise you the PhD placement of your dreams,’ he said, ‘but you won’t have any grant money problems, I promise. Sci-Med will see to that.’

‘Cheers. Sci-Med doesn’t exactly do things by the book, does it?’

‘Let’s say we cherish our independence.’

‘What is it you want me to do?’

‘I’ll need access to your lab out of hours and I need advice about where to look to get information about what Hausman has been up to. I’m assuming Tom North’s stuff will have been cleared out?’

‘The suits did that quite quickly. Why don’t you let me have a sniff around? I’m better placed than anyone else.’

‘Because I don’t want you doing anything that could damage your career... or worse.’

Liam was left to dwell on what ‘worse’ might be for a few moments. ‘Maybe you’re right,’ he agreed, ‘but I’ll keep my ears and eyes open. By the way, it may be irrelevant but blood samples weren’t the only thing your friend Simone sent in the package to the lab.’

‘Really?’

‘There was a computer disk and a note saying that she’d explain when she came to the lab — I think she’d arranged to see Tom the week after she died. I heard Tom tell Dan that he’d had a look but couldn’t make head nor tail of it; it was gobbledegook. To be honest neither of them seemed that fussed. I remember it was in an envelope marked Vaccination schedules.

Steven’s pulse rate rose dramatically. ‘Do you know what happened to the disk?’ he asked.

Liam shook his head slowly. ‘I think Dan was the last to take a look at it. Maybe he still has it. If he gave it back to Tom, it will probably have been cleared out with the rest of his stuff. Why? Is it important?’

‘It wasn’t gobbledegook. It was encrypted. She sent a memory card to me. I think it’s probably the key.’

‘Jesus, but why would anyone go to the trouble of encrypting vaccination schedules?’

‘Who knows?’ said Steven.

‘I could have a look around for the disk if you like,’ said Liam. ‘I mean neither Tom nor Dan seemed to think anything of it so it’s probably not under lock and key.’

‘Don’t take any risks, but if it does happen to be lying around... Look, I’ve kept you long enough,’ said Steven, signalling to the waitress for the bill. ‘Give me your mobile number and I’ll be in touch when I’ve come up with a plan. If I suggest a meeting, assume it’s here or just outside if it’s not during opening hours. Here’s my mobile number: let me know if you have any luck with the disk or if there’s anything you think I should be aware of.’

Twenty one

Steven left Liam and headed off to walk by the river. He was glad that he now had help on the inside, and the revelation about the disk was exciting. If Simone had thought it necessary to keep the disk and its key separate, she might have suspected there was more to it than vaccination schedules. Alternatively, she might simply have assumed that the disk and the card were copies of the same information — proof of faulty vaccination practices — and she’d kept them separate because she’d been unsure about whom among her colleagues she could trust.

Despite making good progress he started to feel very uneasy about what he was planning next. It wouldn’t be the first time he’d crossed the line of what was strictly legal in the course of an investigation — sometimes it was unavoidable — but this time it was different. It was just... downright stupid. That was the depressing conclusion he reached as he leaned on the embankment wall to take in the view.

Below him, about thirty metres away, a man in a knitted hat was sweeping the exposed low-tide mud with a metal detector, wholly captivated by the prospect of unearthing buried treasure. Steven couldn’t help but see the parallel. He’d been planning an unauthorised entry to a university lab to search for the answer to a puzzle but there was something that he’d been failing to properly acknowledge. He was seeking to uncover a secret that the governments of the UK and the US and their intelligence services didn’t want him to know. Was he out of his mind? He had to be if he really believed he was going to find it lying around. The guy with the metal detector had more chance of coming up with the Koh-i-Noor.

Steven was tempted to abandon all thoughts of a break-in, either assisted or unassisted, but steeled himself to go on thinking things through from every angle as he’d done so often in the past. At last he thought he might have found a loophole. The work that Hausman was doing might be top secret but it wasn’t being carried out in a top security lab like those you’d find at Fort Detrick or Porton Down. Why not? Because... the North lab was a more suitable place for the work... but this had to be for scientific not security reasons. That was the compromise that must have been made. The North lab must have expertise that was relevant to the work. There was a connection with polio.