Mulhern’s body was on the floor. He was gagged and his arms were bound behind his back with rope. He was lying in the middle of a large blood-soaked pile of hay and a huge grey stallion stood within inches of Mulhern’s head, eating its fill of the crime scene. Jack moved quickly past the seemingly catatonic Mason, opened the lower half of the stable door and led the grey away from the body. Once the horse was secure, Jack turned to Mason with every intention of tearing a strip off him for freezing, DI or not, but from the expression on Mason’s face as he stared down at the body of the man he’d failed to protect, Jack knew that shouting wasn’t necessary. Mason already knew this was his responsibility.

‘Call it in,’ Jack instructed, ‘DI Mason! Call it in!’ Mason snapped out of his horrified trance and got out his mobile phone.

Mulhern lay on his right side, with his left arm pulled so far round his back that his shoulder was no longer in its socket. His right shin bone was so badly crushed that it lay almost flat against the concrete floor, and the bloodied hoof prints on his shredded trouser leg suggested that the grey had been encouraged to trample this part of Mulhern’s body, over and over.

Torture. Brutal, excruciating torture. Jack crouched down, careful not to touch anything, and examined the body more closely. Someone had carved gouges out of Mulhern’s forearms as well as cutting out little squares of skin. Finally, they’d brought his pain to an end by shattering his skull, most likely with the same crowbar they used on Mathew. Mulhern’s crushed and misshapen head now lay in a pool of dark red gore. Only his thick blond hair and the coagulated mess of hay, blood and brain matter, held his skull together.

Jack heard repeated heavy exhalations as Mason breathed himself calm over Jack’s left shoulder. ‘Ambulance . . . is coming,’ he managed to say between breaths. ‘And DI Lee . . . Fuck . . . Mulhern didn’t know anything. They’d have known that in seconds, so . . . why this? Fuck.’

Jack spun round and looked into Mason’s panicked eyes. Then Mason uttered completely the wrong words: ‘Right . . . well . . . we need to get our story straight with this one, DS Warr.’

If Mason had shown any sign of guilt, instead of the desire for self-preservation, things might have gone differently.