Why had Guy killed her? What made him do it and how, then, did he find the cynicism to take off her dress before he buried her body, and then the wit to throw the dress into the estuary, knowing that when it was found people would believe Alice had drowned?

Guy was a coward, that was for sure. If he had killed Alice accidentally, he wouldn’t have owned up to it. Once, when they were kids, Will had seen Guy attempt to leapfrog one of the illuminated Severn Boar bollards that directed holidaymakers around the park after dark, and he’d knocked it over and broken it. When John Morahan saw the damage and asked what had happened, Guy, looking straight at Will as if daring him to tell, had replied: ‘No idea.’

Will heard footsteps and turned to see a small, scruffy woman, bundled up in boots and a long coat, coming towards him. She was holding a leash attached to a small dog that trotted beside her, its short legs moving fifteen to the dozen. The woman was staring at the ground, not at what lay in front of her so as she approached, Will said: ‘Hi,’ so she wouldn’t be alarmed by his unexpected presence.

The dog immediately started yapping. ‘Sorry!’ said Will. ‘I didn’t mean to make you jump!’

The woman was a silhouette against a sky that glowed with moonlight trapped behind a veil of clouds, but something about her chimed with something in Will. Everything about her and her demeanour felt like a warning to stay away from her, an invisible barrier. But Will knew who she was. Of all the people he could have encountered, she was the one he least wanted to see.

‘Marnie? Marnie Morahan?’

She looked as she always had, older obviously, but with the same determination on her face, wary-eyed and lips set in a defensive line. Her expression was neutral but Will detected fear and he remembered how, after her mother’s death, Marnie had been like a small, wild animal, always expecting to be chased away. He hadn’t thought about her much in years. For long swathes of time he’d forgotten she existed, but now she was here, in front of him, he remembered all she’d been through and Angharad telling him she’d become completely mute after Alice disappeared; that psychological trauma could do that to a sensitive child. He remembered how he’d used and then discarded her and felt a rush of shame. She’d been very young. Perhaps she’d forgotten.

‘It’s me, Marnie,’ he said, ‘Will Jones.’