Rosie crammed in a handful and washed them down with ale. “Sorry,” she said, wishing she’d bought two packets. “I guess we both have minds like sieves.”

“On that note…” Steph paused to drink her mojito with her pinkie raised. “Social Services are not happy with you. They want to know why you interviewed Lily Parker without a chaperone present.”

The froth on Rosie’s pint went up her nose as she inhaled sharply. She swallowed her mouthful and set the glass down, waiting out a burst of saxophone and the spike in her blood pressure. “It was hardly a bloody interview, Steph. We spoke for about five minutes. What would they rather I’d done? Ignored the kid and sent her on her way? She was distraught, and she obviously needed someone to talk to.”

“I was there to talk to her,” Steph said. “In an official capacity, in a structured interview.”

Rosie chewed that one over for a couple of seconds. The alcohol had hit her empty stomach hard and given her a quick, pleasant buzz, which allowed her to face down Steph’s self-righteous indignation with unusual equanimity. “Did Lily say much? When you talked to her officially, with the chaperone present?” The question was rhetorical; she’d overheard Ray ranting about the wasted hour before he stomped off to recall the door-to-doors. She watched the colour rise on Steph’s cheeks, pink darkening to a florid red.

“Fuck off, Roz,” Steph said, slamming emphasis on the nickname she knew Rosie loathed. “Nothing she told you was on the record. It’s all inadmissible.”

“She’s not our perp, Steph,” Rosie said quietly. “She’s an eleven-year-old who’s just lost her big brother, the brother who bought her stuff he shouldn’t have been able to afford, who flashed twenty-pound notes at her and had a brand new PS4 hidden away in his room. From what Lily said, their mum doesn’t know anything about this, and it’s an important lead, so does it really matter how we came by the information?”

“It matters that we follow the fucking rules,” Steph said. “That may be an unfamiliar concept to you, but I can’t afford to step outside the lines whenever the fancy strikes me.”

“Ouch.” Rosie finished her pint and reached for her coat. “That was below the belt.”

“Aw, c’mon.” Steph raised both hands, as if calling a ceasefire now that she’d prevailed. “You know I didn’t mean anything by it. Please don’t go.”

Rosie fastened her zip right up to her chin. The bar was hot and airless, but she was still cold. “It’s been a really long day. You stay. I’ll get a taxi.”