‘It has the smell of something else, if you ask me. Vomit and piss.’

‘And just a dash of dog shit,’ conceded Jack. ‘Labrador, I’d say.’

‘Now you’re just showing off.’

‘Well, watch your step. And you wanna take a look at him while I check out the victim?’ Jack pointed to a hunched figure opposite, and then strode off down the alleyway into the crime scene, his long military coat flapping around him.

Police Constable Jimmy Mitchell had his head in his hands when Gwen went over to him. She didn’t recognise him immediately. She only saw the burly policeman sitting on the kerb, where he clutched one leg of the nearby road sign as though he was frightened to let go. The uniform, the fluorescent jacket, should have given him an air of authority. Instead, he was like a lost child. His posture looked defeated and his peaked cap was discarded on the pavement beside him. There was a fresh pool of vomit near his feet. He looked up, and she almost didn’t know him then either, because his face was grey with shock. She’d worked for a while with Mitchell on late patrols, weeks ago, the usual boring driving tour of night-time Cardiff, enlivened only by the chance to break up a bottle fight in a dingy pub at closing time.

‘Mitch?’ Gwen asked him. ‘Oh God, what’s happened to you?’

Mitch opened his mouth, but for a moment couldn’t speak. There were flecks of vomit in his moustache. He gestured wordlessly back down the alley. Should she leave him to take a look, or stay with him to make sure he wasn’t injured or badly in shock? An angry shout from Jack decided the matter, and she hurried down the alley to join him.

Jack stood by the corpse, his hands on his hips. He tilted his head up towards the blue afternoon sky and screwed up his eyes, whether from the bright sun or from sheer exasperation it wasn’t clear to Gwen. ‘What do you see?’