“Anyway,” said Harper, “I’ve been told by my boss to leave the case alone. Which is why I’m here on my lunch hour, and not on work time.”

“You don’t have a lunch hour.” Amy cast her eyes about the car. “And, I don’t see any lunch.”

It was true, there was no such thing as a lunch hour at the station. You ate at your desk. All of the computer keyboards had a film of supermarket mayo and a dusting of crisp crumbs. “Well, I’m on my way to the shop, if you must know. We are allowed to do that.”

Amy considered this information for a while. “None of this actually explains why you’re here. Precisely here, right now, watching that car, which I am assuming from what you’ve said, belongs to Tranter. How did that come about?”

“Oh, that. Well, I was going to check the trampled bushes again, in the daylight, just to see if there was anything I’d missed. As I pulled up near the house I happened to see Patrick getting into his car. So, I followed.”

“Makes sense. Nothing better to do. On your way to the shop.”

“Right.”

“And, it’s a lovely day for it.”

“Yes,” said Harper, with less confidence.

“For a bit of freelance snooping.”

“Well, I don’t see it quite like that—”

“Not that I’m judging. Lord knows, that’s my entire existence. Oh wait, who’s this?”

A thin woman with dark hair approached the entrance to the office car park. She removed a mobile phone from a small red handbag and pressed on its screen, then held it to her ear. After a short conversation, she put the phone back in her bag and leaned on the bonnet of Patrick Tranter’s car with her arms folded.

Harper looked through her binoculars at the woman, who was very pale and dressed in a long black T-shirt dress and flip-flops. Probably in her early twenties, the woman seemed as if she’d been crying, and her dark hair was greasy and limp. But, it was clear she was a naturally beautiful girl, even with puffy eyes and without make-up.

“I think this must be a friend of Mr Tranter’s.”

“She doesn’t look too friendly to me,” said Amy, before popping a walnut into her mouth and crunching down on it. Patrick appeared at the office door and pushed it open. He walked across the car park towards the woman and stopped several metres away from her, his fists shoved deep in his pockets. “She looks as if she might scratch his eyes out.”

“Who do you think she is?” said Harper, lowering the binoculars.

“Why don’t we find out? Let’s do a stroll-by.”

“Oh, I can’t. He knows me.”