The ambulance bounces along the track and picks up the main road. At the wheel is the paramedic who sat on the ground and chatted to Alfie on his branch for half an hour. She beeps the horn and waves to the fire crew and the two police officers. The fireman standing with Will raises his hand to her.

Another life saved, Will thinks. Just a little wave as if to say, Nice to see you. Catch you next time we need to head off a tragedy. All in a day’s work.

‘So long, anyway. Give your friend my best.’

He nods as the fireman jogs back to his colleagues.

Will had never meant to brink this quite like he did. Since his encounter in the darkroom, he knew it was supposed to happen this morning. And roughly where Alfie would be. But that’s all he’d been told – all that had made it through to him, anyway. He’s been up all night, roaming the marshes. By four a.m., with the fog thickening and his calls unanswered, he knew his only option was to place an emergency call as soon as he located Alfie. Anything else was just too risky. What the hell do you say to someone who doesn’t want to live any more? Will’s asked himself that question all night and still has no answer. He’s glad he made the call, that’s for sure.

Did I save his life? Will wonders. Without me, he’d be dead now, surely.

It’s someone who’s dying, someone who’s going to die very soon – that’s what he and Ms Calloway surmised about Will’s unseen messenger. Somebody who needs his help.

Has it been Alfie all along? Is this over now?

The fog has thinned and Will gazes across the marsh and out to the cold steel sea.

Think about it: Alfie jumps, he stops breathing, his heart grinds to a halt, and the process begins – of dying, of his mind fading away. That process feels to Alfie like many weeks, his consciousness looping back to early September. And in that extra time, Alfie decides he doesn’t want to go after all, so he follows the one person who might be able to stop him. Builds that person’s trust, makes them believe in him, in themselves, nurtures them till they are the person they need to be to stop him.

It was Alfie, Will thinks. It must have been. He dragged me out of my shell, made me befriend his other self, showed me how to change things. And here we are, on a frozen November morning, with everything fixed.

It’s over.