“He doesn’t give a damn about the course of justice, or Jenny’s debt to society, or any of that stuff. He just cares about Jenny. He has to know what she wants to do. If he confessed to you guys, that’s why: so she can get the chance.” That twitch again. “Probably he’d think I’m being selfish, trying to save her just because I want her here. Maybe I am. I don’t care.”

Trying to save her. She was on my side, if I could just find a way to use that. “Then tell him Jenny’s already dead. He knows she’ll be out of hospital any day: tell him they let her out, and she took the first chance she got. If she’s not there to be protected any more, he might as well go ahead and save his own arse.”

Fiona was already shaking her head. “He’d know I was lying. He knows Jenny. There’s no way she’d … She wouldn’t go without leaving a note to get him out. No way.”

We had lowered our voices, like conspirators. I said, “Then do you think you could convince Jenny to make an official statement? Beg her, guilt-trip her, talk about the children, about Pat, about Conor; say whatever you need to say. I’ve had no luck, but coming from you—”

She was still shaking her head. “She’s not going to listen to me. Would you, if you were her?”

Both our eyes went to that closed door. “I don’t know,” I said. I would have been boiling over with frustration—for a second I thought of Dina, gnawing at her arm—if I had had anything left. “I haven’t got a clue.”

“I don’t want her to die.”

All of a sudden Fiona’s voice was thick and wobbling. She was about to cry. I said, “Then we need evidence.”

“You said you don’t have any.”

“I don’t. And at this point, we’re not going to get any.”

“Then what do we do?” She pressed her fingers to her cheeks, swiped away tears.

When I took a breath, it felt like it was made of something more volatile and violent than air, something that burned its way through membranes into my blood. I said, “There’s only one possible solution that I can think of.”

“Then do it. Please.”

“It’s not a good solution, Ms. Rafferty. But very occasionally, desperate times can call for desperate measures.”

“Like what?”

“Rarely, and I’m talking very rarely, a crucial piece of evidence shows up through the back door. Through channels that you could call less than one hundred percent legit.”

Fiona was staring at me. Her cheeks were still wet, but she had forgotten about crying. She said, “You mean you could—” She stopped, started again more carefully. “OK. What do you mean?”

It happens. Not often, nowhere near as often as you probably think, but it happens. It happens because a uniform lets some little smart-arse get under his skin; it happens because a lazy prick like Quigley gets jealous of the real detectives and our solve rates; it happens because a detective knows for a fact that this guy is about to put his wife in hospital or pimp a twelve-year-old. It happens because someone decides to trust his own mind over the rules we’ve sworn to follow.