Free The Enemy by Lee Child

big question, obviously."
    "Did he have an answer?"
    "Not at first. Then he said it was because he heard a vehicle leaving in a hurry."
    "What vehicle?"
    "He said it was a big engine, revving hard, taking off fast, like a panic situation."
    "Did he see it?"
    Summer just shook her head.
    "Makes no sense," I said. "A vehicle implies a call girl, and I doubt if they have many call girls here. And why would Kramer need a call girl anyway, with all those other hookers right there in the bar?"
    Summer was still shaking her head. "The kid says the vehicle had a very distinctive sound. Very loud. And diesel, not gasoline. He says he heard the exact same sound again a little later on."
    "When?"
    "When you left in your Humvee."
    "What?"
    Summer looked right at me. "He says he checked Kramer's room because he heard a military vehicle peeling out of the lot in a panic."

FOUR
    We went back across the road to the motel and made the kid tell the story all over again. He was surly and he wasn't talkative, but he made a good witness. Unhelpful people often do. They're not trying to please you. They're not trying to impress you. They're not making all kinds of stuff up, trying to tell you what you want to hear.
    He said he was sitting in the office, alone, doing nothing, and at about eleven twenty-five in the evening he heard a vehicle door slam and then a big turbo-diesel start up. He described sounds that must have been a gearbox slamming into reverse and a four-wheel-drive transfer case locking up. Then there was tyre noise and engine noise and gravel noise and something very large and heavy sped away in a big hurry. He said he got off his stool and went outside to look. Didn't see the vehicle. "Why did you check the room?" I asked him.
    He shrugged. "I thought maybe it was on fire."
    "On fire?"
    "People do stuff like that, in a place like this. They set the room on fire. And then high-tail out. For kicks. Or something. I don't know. It was unusual."
    "How did you know which room to check?"
    He went very quiet at that point. Summer pressed him for an answer. Then I did. We did the good cop, bad cop thing. Eventually he admitted it was the only room rented for the whole night. All the others were renting by the hour, and were being serviced by foot traffic from across the street, not by vehicles. He said that was how he had been so sure there was never a hooker in Kramer's room. It was his responsibility to check them in and out. He took the money and issued the keys. Kept track of the comings and the goings. So he always knew for sure who was where. It was a part of his function. A part he was supposed to keep very quiet about.
    "I'll lose my job now," he said.
    He got worried to the point of tears and Summer had to calm him down. Then he told us he had found Kramer's body and called the cops and cleared all the hourly renters out for safety's sake. Then Deputy Chief Stockton had shown up within about fifteen minutes.
    Then I had shown up, and when I left some time later he recognized the same" vehicle sounds he had heard before. Same engine noise, same drivetrain noises, same tyre whine. He was convincing. He had already admitted that hookers used the place all the time, so he had no more reason to lie. And Humvees were still relatively new. Still relatively rare. And they made a distinctive noise. So I believed him. We left him there on his stool and stepped outside into the cold red glow of the Coke machine.
    "No hooker," Summer said. "A woman from the base instead."
    "A woman officer," I said. "Maybe fairly senior. Someone with permanent access to her own Humvee. Nobody signs out a pool vehicle for an assignation like that. And she's got his briefcase. She must have."
    "She'll be easy to find. She'll be in the gate log, time out, time in."
    "I might have even passed her on the road. If she left here at eleven twenty-five she wasn't back at Bird before about twelve fifteen. I was leaving around then."
    "If she went straight back to the