“They’re students,” I said. “Book bags. They’d been food shopping-the carrier bags from Dunne’s. She’s better off than he is; her jacket was expensive, but he had a patch on his jeans, and not in a trendy way.”

“They a couple? Friends? Flatmates?”

“A couple. They walked closer than friends, tilted their heads closer.”

“They going out long?”

I liked this, the new way my mind was working. “A while, yeah,” I said. Frank cocked an eyebrow like a question, and for a moment I wasn’t sure how I knew; then it clicked. “They didn’t look at each other when they were talking. New couples look at each other all the time; established ones don’t need to check in as often.”

“Living together?”

“No, or he’d have automatically gone for his keys as well. That’s her place. She has at least one flatmate, though. They both looked up at a window: checking to see if the curtains were open.”

“How’s their relationship?”

“Good. She made him laugh-guys mostly don’t laugh at a girl’s jokes unless they’re still at the chat-up stage. He was carrying both the Dunne’s bags, and she held the door open for him before she went in: they look after each other.”

Frank gave me a nod. “Nicely done. Undercover’s half intuition-and I don’t mean psychic shite. I mean noticing things and analyzing them, before you even know you’re doing it. The rest is speed and balls. If you’re going to say something or do something, you do it fast and you do it with total conviction. If you stop to second-guess yourself, you’re fucked, possibly dead. You’ll be out of touch a lot, the next year or two. Got family?”

“An aunt and uncle,” I said.

“Boyfriend?”

“Yes.”

“You’ll be able to contact them, but they won’t be able to contact you. They going to be OK with that?”

“They’ll have to be,” I said.

He was still slouching easily against the window frame, but I caught the sharp glint of blue: he was watching me hard. “This isn’t some Colombian cartel we’re talking about, and you’ll be dealing mostly with the lowest ranks-at first, anyway-but you’ve got to know this job isn’t safe. Half these people are binned out of their heads most of the time, and the other half are very serious about what they do, which means none of them would have any problem with the idea of killing you. That make you nervous?”

“No,” I said, and I meant it. “Not at all.”

“Lovely,” said Frank. “Let’s get coffee and get to work.”

It took me a minute to realize that that was it: I was in. I’d been expecting a three-hour interview and a stack of weird tests with inkblots and questions about my mother, but Frank doesn’t work like that. I still don’t know where, along the way, he made the decision. For a long time, I waited for the right moment to ask him. Now I’m not sure, any more, whether I want to know what he saw in me; what it was that told him I would be good at this.

We got burnt-tasting coffee and a packet of chocolate biscuits from the canteen, and spent the rest of the day coming up with Alexandra Madison. I picked the name-“You’ll remember it better that way,” Frank said. Madison, because it sounds enough like my own surname to make me turn around, and Lexie because when I was a kid that was the name of my imaginary sister. Frank found a big sheet of paper and drew a timeline of her life for me. “You were born in Holles Street Hospital on the first of March 1979. Father, Sean Madison, a minor diplomat, posted in Canada -that’s so we can pull you out fast if we need to: give you a family emergency, and off you go. It also means you can spend your childhood traveling, to explain why nobody knows you.” Ireland is small; everyone’s cousin’s girlfriend went to school with you. “We could make you foreign, but I don’t want you fucking about with an accent. Mother, Caroline Kelly Madison. She got a job?”

“She’s a nurse.”

“Careful. Think faster; keep an eye out for implications. Nurses need a new license for every country. She trained, but she quit working when you were seven and your family left Ireland. Want brothers and sisters?”

“Sure, why not,” I said. “I’ll have a brother.” There was something intoxicating about this. I kept wanting to laugh, just at the lavish giddy freedom of it: relatives and countries and possibilities spread out in front of me and I could pick whatever I wanted, I could grow up in a palace in Bhutan with seventeen brothers and sisters and a personal chauffeur if I felt like it. I shoved another biscuit into my mouth before Frank could see me smiling and think I wasn’t taking this seriously.

“Whatever your heart desires. He’s six years younger, so he’s in Canada with your parents. What’s his name?”

“Stephen.” Imaginary brother; I had an active fantasy life as a kid.

“Do you get on with him? What’s he like? Faster,” Frank said, when I took a breath.

“He’s a little smart-arse. Football-mad. He fights with our parents all the time, because he’s fifteen, but he still talks to me…”

Sun slanting across the scarred wood of the desk. Frank smelled clean, like soap and leather. He was a good teacher, a wonderful teacher; his black Biro scribbled in dates and places and events, and Lexie Madison developed out of nothing like a Polaroid, she curled off the page and hung in the air like incense smoke, a girl with my face and a life from a half-forgotten dream. When did you have your first boyfriend? Where were you living? What was his name? Who dumped who? Why? Frank found an ashtray, flipped a Player’s out of his packet for me. When the sun bars slid off the desk and the sky started to dim outside the window, he spun his chair around, took a bottle of whiskey off a shelf and spiked our coffees: “We’ve earned it,” he said. “Cheers.”

We made her a restless one, Lexie: bright and educated, a good girl all her life, but brought up without the habit of settling and never learned the knack. A little naďve maybe, a little unguarded, too ready to tell you anything you asked without thinking twice. “She’s bait,” Frank said bluntly, “and she has to be the right bait to make the dealers rise. We need her innocent enough that they won’t consider her a threat, respectable enough to be useful to them, and rebellious enough that they won’t wonder why she wants to play.”

By the time we finished, it was dark. “Nice work,” Frank said, folding up the timeline and passing it to me. “There’s a detective training course starting in ten days; I’ll get you into that. Then you’ll come back here and I’ll work with you for a while. When UCD starts back in October, you’ll go in.”

He hooked a leather jacket off the corner of the shelves, switched off the light and shut the door on the dark little office. I walked back to the bus station dazzled, wrapped in magic, floating in the middle of a secret and a brand-new world, with the timeline making little crackling sounds in the pocket of my uniform jacket. It was that quick, and it felt that simple.

I’m not going to get into the long, snarled chain of events that took me from Undercover to Domestic Violence. The abridged version: UCD’s premier speed freak got paranoid and stabbed me, wounded-in-the-line-of-duty got me a place on the Murder squad, the Murder squad got to be a head-wrecker, I got out. It had been years since I’d thought about Lexie and her short shadowy life. I’m not the type to look back over my shoulder, or at least I try hard not to be. Gone is gone; pretending anything else is a waste of time. But now I think I always knew there would be consequences to Lexie Madison. You can’t make a person, a human being with a first kiss and a sense of humor and a favorite sandwich, and then expect her to dissolve back into scribbled notes and whiskeyed coffee when she no longer suits your purposes. I think I always knew she would come back to find me, someday.