And the reports made disturbing reading. He hadn’t felt ill before, but Cooper was more than ready to be sick by the time he’d finished.

Meth, speed, crystal, ice, glass, crank, tweak, yaba. Call it whatever you liked, methamphetamine was highly addictive, producing a high that could last from twelve hours to a few days. The latest assessments warned that it had the potential to rival crack cocaine as the most dangerous drug in the country.

Only this year, methamphetamine had been upgraded from a Class B substance to Class A, which meant that anyone caught dealing it could receive a life sentence, and even possession got you seven years. On the street, it was generally found as an odourless, white, bitter-tasting powder, though it could also turn up in the form of pills, capsules and large crystals. Frequently snorted, but also used orally, smoked, and injected.

Methamphetamine was being manufactured in Britain as well as imported by a Filipino criminal network. It had begun to spread throughout the UK and was thought to be available in almost every city, according to the intelligence. It was increasingly popular among clubbers, and had started to enter mainstream drug use within the last few years. Hence, a rising demand that created a lucrative industry for unscrupulous entrepreneurs with access to the right sort of location.

Cooper watched Gavin Murfin dragging his heels towards the door as he was summoned to see the doctor. He wasn’t sure what order they were being called in. Reverse alphabetical, maybe. Or the oldest first. He’d have a while to wait yet, anyway.

‘Good luck, Gavin,’ he called.

‘Yeah, thanks.’

The right sort of location. That was the heart of the matter. Cooper had speculated about the laundering of red diesel going on somewhere like Pity Wood Farm, but crystal meth production required a remote location, too. Clandestine labs were often run in rural places because noxious smells could dissipate unnoticed.

The advice said that one of the more obvious signs of a methamphetamine production lab in operation was an odour similar to that of cat urine. Well, yes – the smell had been obvious. But he’d been too stupid to think of anything apart from the presence of cats.

Cooper’s blood ran cold when he read the next paragraph. Meth labs also gave off other noxious fumes, such as phosphine gas, mercury vapours, lead, solvent fumes such as chloroform, iodine vapours and white phosphorus.

The back of his throat constricted at the thought. Cooper wondered about the fate of the forensics teams who had been digging up the yard for several days, sifting through the rubbish and searching the contents of the kitchen. He thought about Liz, and prayed she was safe.