The CID team and Scenes of Crime waited at a distance for their chance to go in. On a signal from the operational commander, the armed officers roared up the roadway in their unmarked vehicles and jumped out, shouting orders that could be heard from the street. Within a few minutes, they had contained the scene, and four suspects were on the ground with plastic cuffs on their wrists, being searched for weapons.

‘Well, that was easy enough,’ said DI Hitchens when the detectives moved in. ‘I like it when things go well. If we find what we’re looking for in this place, I’ll buy you all a drink down at the pub to celebrate. Two drinks, since it’s Christmas.’

They watched the SOCOs climb into their protective suits and breathing apparatus, and enter the premises. Before long, the doors of the unit slid open and they could all see inside. Long benches were filled with equipment – rubber tubing, glass jars, a row of electric cookers. Even from outside the building, the whiff of fumes was enough to make officers begin coughing and backing away towards cleaner air.

Cooper scented the stench of ammonia, much more powerful than it had been at Pity Wood Farm. He knew better now, and he didn’t look around for any cats.

Hitchens gave his detectives a thumbs up, then replaced it with a two-fingered salute. Victory? Or just two drinks down at the pub?

The clear-up and removal of evidence from the industrial unit at Staveley would be a long business. Fry and Cooper left after a couple of hours’ talking to the neighbouring tenants and drove back towards Edendale.

The suspects from the operation would have been processed by now and would be residing in the custody suite. But interviews wouldn’t be taking place until senior officers were happy that all the facts were in place, and that might not be for twenty-four hours yet. Drinks were definitely looking a possibility.

Cooper took a hands-free call on his mobile as they were heading out of Staveley into heavy traffic through Brimington. It was the officer on con obs duty at the hospital, keeping a constant watch on Raymond Sutton in case he made another attempt on his own life.

Sutton had begun talking again, and the officer had made detailed notes. Con obs was a really boring duty.

‘Raymond Sutton is claiming that his brother Alan died falling downstairs during an argument,’ Cooper explained to Fry when he finished the call. ‘He says he and Derek set off to put their brother into a car to take him to hospital, because it takes so long for an ambulance to get to Pity Wood. But before they got him in the car, they realized he was dead.’

‘Go on.’