When she pulled in through the north entrance, there was only one other car waiting. It was a white Toyota Camry, parked next to the trail that led out to the East Ridge. She slipped the Oldsmobile in beside it, her wheels kicking up red dust as she braked, and inside the Camry she saw a man in his sixties, trim, with a moustache and grey hair. It was hard to see much more than that: the sun was starting to come up now, cutting across the eastern flanks of the Santa Monica Mountains, and it filled his front windows with colour. Jo killed the engine and got out at the same time as he did.

‘Detective Kader?’ the man said across the roof of the Camry.

She nodded. ‘Yeah, that’s me.’

‘I’m Ray Callson.’

They met beside the trunk of the Camry and shook hands. He was over six feet, in good shape, handsome in a weathered, fatherly sort of way, but when he moved it was slowly. Somehow, to Jo, it didn’t feel like it was down to a physical impairment – his stride was smooth, his grip strong, his green eyes sharp and focused; instead, it felt like something else was affecting him, something more abstract and hidden. He had the kind of look that cops got sometimes, especially after a lot of years: a fatigue that wouldn’t wash out, a slow, corrosive burn. Maybe it was a case. Maybe it was this case. Maybe this was what you became when you worked in a city like this your whole life.

Callson popped the trunk of the Camry and took out a blue three-ring binder. It was an LAPD murder book. On the other side of their cars, the trail split, one of them heading south, pretty much through the centre of the park, the other immediately climbing west. He used the binder to gesture to the western branch.

‘You up for a walk, Detective?’

She nodded. ‘Absolutely.’