Silence, and I pictured Rosalind holding the door open and staring at her, gauging; Cassie's face upturned and tense, her hands deep in the pockets of her suede jacket. In the background someone-Margaret-called something. Rosalind snapped, "It's for me, Mother," and the door slammed shut.

"Well?" Rosalind inquired.

"Could we…" A rustle: Cassie shifting nervously. "Could we maybe go for a walk or something? This is pretty private."

That must have piqued Rosalind's interest, but her voice didn't change. "I'm actually getting ready to go out."

"Just five minutes. We can walk round the back of the estate, or something… Please, Miss Devlin. It's important."

Finally she sighed. "All right. I suppose I can give you a few minutes."

"Thanks," Cassie said, "I really appreciate it," and we heard them going down the pathway again, the swift decisive taps of Rosalind's heels.

It was a sweet morning, a soft morning; the sun was skimming off last night's mist, but there had still been wispy layers, over the grass and hazing the high cool sky, when we got into the van. The speakers magnified the twitter of blackbirds, the creak and clank of the estate's back gate, then Cassie's and Rosalind's feet swishing through the wet grass along the edge of the wood. I thought of how beautiful they would look, to some early watcher: Cassie windblown and easy, Rosalind fluttering white and slender as something from a poem; two girls in the September morning, glossy heads under the turning leaves and rabbits scampering away from their approach.

"Can I ask you something?" Cassie said.

"Well, I did think that was why we were here," Rosalind said, with a delicate inflection implying that Cassie was wasting her valuable time.

"Yeah. Sorry." Cassie took a breath. "OK. I was wondering: how did you know about…"

"Yes?" Rosalind prompted politely.

"About me and Detective Ryan." Silence. "That we were…having an affair."

"Oh, that!" Rosalind laughed: a tinkling little sound, emotionless, barely even a speck of triumph. "Oh, Detective Maddox. How do you think?"

"I thought probably you guessed. Or something. That maybe we didn't hide it as well as we thought. But it just seemed…I couldn't stop wondering."

"Well, you were a little bit obvious, weren't you?" Mischievous, chiding. "But no. Believe it or not, Detective Maddox, I don't spend a lot of my time thinking about you and your love life."

Silence again. O'Kelly picked caramel out of his teeth. "Then how?" Cassie asked finally, with an awful note of dread.

"Detective Ryan told me, of course," Rosalind said sweetly. I felt Sam's eyes and O'Kelly's flicking to me, and bit the inside of my cheek to stop myself denying it.

This is not an easy thing to admit, but until that moment I had held out some craven speck of hope that this had all been a hideous misunderstanding. A boy who would say anything he thought you wanted to hear, a girl made vicious by trauma and grief and my rejection on top of it all; we could have misinterpreted in any one of a hundred ways. It was only in that moment, in the ease of that gratuitous lie, that I understood that Rosalind-the Rosalind I had known, the bruised, captivating, unpredictable girl with whom I had laughed in the Central and held hands on a bench-had never existed. Everything she had ever shown me had been constructed for effect, with the absorbed, calculating care that goes into an actor's costume. Underneath the myriad shimmering veils, this was something as simple and deadly as razor wire.

"That's bollocks!" Cassie's voice cracked. "He would never fucking tell-"

"Don't you dare swear at me," Rosalind snapped.

"Sorry," Cassie said, subdued, after a moment. "I was just-I just didn't expect that. I never thought he would tell anyone. Ever."

"Well, he did. You should be more careful about who you trust. Is that all you wanted to ask me?"

"No. I need to ask you a favor." Movement: Cassie running a hand through her hair, or across her face. "It's against the rules to-to fraternize with your partner. If our boss finds out, we could both get fired, or reverted back to uniform. And this job…this job means a lot to us. To both of us. We worked like crazy to get onto this squad. It would break our hearts to be thrown off it."

"You should have thought of that before, shouldn't you?"

"I know," Cassie said, "I know. But is there any chance you could-just not say anything about this? To anyone?"

"Cover up your little affair. Is that what you mean?"

"I…yeah. I suppose so."

"I'm not sure why you feel I should do you any favors," Rosalind said coolly. "You've been horribly rude to me every time we've met-until now, when you want something from me. I don't like users."

"I'm sorry if I was rude," Cassie said. Her voice sounded strained, too high and too fast. "I really am. I think I felt-I don't know, threatened by you… I shouldn't have taken it out on you. I apologize."

"You did owe me an apology, actually, but that's beside the point. I don't mind the way you insulted me, but if you could treat me that way, I'm sure you do it to other people, too, don't you? I don't know if I should protect someone who behaves so unprofessionally. I'll have to have a little think about whether it's my duty to tell your supervisors what you're really like."

"The little bitch," Sam said softly, not looking up.

"She wants a boot up the hole," O'Kelly muttered. Despite himself, he was starting to look interested. "If I'd ever given that kind of cheek to someone twice my age…"

"Look," Cassie said desperately, "it's not just about me. What about Detective Ryan? He's never been rude to you, has he? He's mad about you."

Rosalind laughed modestly. "Is he really?"

"Yeah," Cassie said. "Yeah, he is."

She pretended to think about it. "Well…I suppose if you were the one chasing him, then the affair wasn't really his fault. It might not be fair to make him suffer for it."

"I guess I was." I could hear the humiliation, stark and uncamouflaged, in Cassie's voice. "I was the…I was always the one who initiated everything."

"And how long has this been going on?"

"Five years," Cassie said, "off and on." Five years earlier Cassie and I had never met, hadn't even been posted in the same part of the country, and I realized suddenly that this was for O'Kelly's benefit, to prove herself a liar in case he had any lingering suspicions about us; realized, for the first time, quite what a fine and double-edged game she was playing.

"I would need to know it was over, of course," Rosalind said, "before I could think about covering up for you."

"It's already over. I swear, it is. He…he ended it a couple of weeks ago. For good, this time."

"Oh? Why?"

"I don't want to talk about it."

"Well, that's not really your choice."

Cassie took a breath. "I don't know why," she said. "That's the honest-to-God truth. I've tried my best to ask him, but he just says it's complicated, he's mixed up, he's not able for a relationship right now-I don't know if there's someone else, or… We're not speaking to each other any more. He won't even look at me. I don't know what to do." Her voice was trembling badly.

"Listen to that," O'Kelly said, not quite admiringly. "Maddox missed her calling. Should've gone on the stage."

But she wasn't acting, and Rosalind smelled it. "Well," she said, and I heard the tiny smirk in her voice, "I can't say I'm surprised. He certainly doesn't talk about you like a lover."

"What's he say about me?" Cassie asked, helplessly, after a second. She was flashing her unarmored spots to draw the blows; she was deliberately letting Rosalind hurt her, maul her, delicately peel back layers of pain to feed on them at her leisure. I felt sick to my stomach.