With a splintering crackle, the garda with the pry bar forced the shed door open. As soon as he did so, the air rushed in, and the inside of the shed exploded into a fireball. Katie went around to the open door, shielding her face with her hand. Somehow, in the middle of that inferno, Nolan Carroll was still standing, and he managed to take two or three jerky steps towards the door. Tins of gloss paint were bursting and bubbling on either side of him and blazing loops were dripping down from the shelves.

He nearly managed to reach the door, although by now he must have been blind, and his nerve endings all seared away, so that he wouldn’t have been able to feel anything. He raised one arm as if in salute, or an appeal for help. But then he sagged and fell forward, half in and half out of the shed. He lay at Katie’s feet, blackened and smouldering now, with only a few small flames flickering across his back.

Detective Cullen came panting up with the fire extinguisher, and squirted foam all over him, and then squirted more into the open shed door. It was futile, though. The whole shed was burning too ferociously, spitting and popping, with pungent black smoke piling up into the clouds, peppered with sparks.

Katie waited for a minute or two. She felt numb. Nolan Carroll’s body reminded her too painfully of Garrett, sitting incinerated in his car. After a while she laid her hand on Detective Walsh’s shoulder because she could see how shocked she was, too. Then, without a word, she turned away and went back into the house. As she made her way around the kitchen table, she could hear the fire brigade’s sirens approaching.

She found Mrs Carroll sitting on her own in the living room, her hands clasped together, with tears streaming down her cheeks. Katie was aware that her clothes smelled of smoke.

Mrs Carroll looked up at her. ‘Did he really do that? Push Roisin and her baby into the river?’

‘Yes, Mrs Carroll. We have every reason to believe that it was him.’

‘It must have been him. He always used to say that if he ever committed a mortal sin, he would take his own life, rather than allow God to punish him for all eternity. I never met another man so frightened of God.’

‘You saw the fire?’

Mrs Carroll nodded.

‘I’m afraid that he’s passed away,’ Katie told her. ‘We tried to get him out of there, but he’d bolted the door. There was nothing we could do to save him.’