Tripwire

just enough to take the pallor off his skin without provoking the risk of melanomas. He walked whenever he could. Going home, he would get off the subway a stop short and hike the rest of the way, fast enough to get his breath going and his heartbeat raised, like the stuff he’d read said he should. And during the workday, he would persuade O’Hallinan to park the prowl car somewhere that would give them a short walk to wherever it was they were headed.
    O’Hallinan had no interest in aerobic exercise, but she was an amiable woman and happy enough to cooperate with him, especially during the summer months, when the sun was shining. So she put the car against the curb in the shadow of Trinity Church and they approached the World Trade Center on foot from the south. It gave them a brisk six-hundred-yard walk in the sun, which made Sark happy, but it left the car exactly equidistant from a quarter of a million separate postal addresses, and with nothing on paper in the squad room it left nobody with any clue about which one of them they were heading for.
    YOU WANT A ride back to the airport?” DeWitt asked.
    Reacher interpreted the offer as a dismissal mixed in with a gesture designed to soften the stonewall performance the guy had been putting up. He nodded. The Army Chevrolet would get them there faster than a taxi, because it was already waiting right outside with the motor running.
    “Thanks,” he said.
    “Hey, my pleasure,” DeWitt said back.
    He dialed a number from his desk and spoke like he was issuing an order.
    “Wait right here,” he said. “Three minutes.”
    Jodie stood up and smoothed her dress down. Walked to the windows and gazed out. Reacher stepped the other way and looked at the mementoes on the wall. One of the photographs was a glossy reprint of a famous newspaper picture. A helicopter was lifting off from inside the embassy compound in Saigon, with a crowd of people underneath it, arms raised like they were trying to force it to come back down for them.
    “You were that pilot?” Reacher asked, on a hunch.
    DeWitt glanced over and nodded.
    “You were still there in ‘75?”
    DeWitt nodded again. “Five combat tours, then a spell on HQ duty. Overall, I guess I preferred the combat.”
    There was noise in the distance. The bass thumping of a powerful helicopter, coming closer. Reacher joined Jodie at the window. A Huey was in the air, drifting over the distant buildings from the direction of the field.
    “Your ride,” DeWitt said.
    “A helicopter?” Jodie said.
    DeWitt was smiling. “What did you expect? This is the helicopter school, after all. That’s why these boys are down here. It ain’t driver’s ed.”
    The rotor noise was building to a loud wop-wop-wop. Then it slowly blended to a higher-pitched whip-whip-whip as it came closer and the jet whine mixed in.
    “Bigger blade now,” DeWitt shouted. “Composite materials. Not metal anymore. I don’t know what old Vic would have made of it.”
    The Huey was sliding sideways and hovering over the parade ground in front of the building. The noise was shaking the windows. Then the helicopter was straightening and settling to the ground.
    “Nice meeting you,” DeWitt shouted.
    They shook his hand and headed out. The MP sergeant at the desk nodded to them through the noise and went back to his paperwork. They went down the stairs and outside into the blast of heat and dust and sound. The copilot was sliding the door for them. They ran bent-over across the short distance. Jodie was grinning and her hair was blowing everywhere. The copilot offered his hand and pulled her up inside. Reacher followed. They strapped themselves into the bench seat in back and the copilot slid the door closed and climbed through to the cabin. The familiar shudder of vibration started up as the craft hauled itself into the air. The floor tilted and swung and the buildings rotated in the windows, and then their roofs were visible, and then the outlying grassland, with the highways laid through it like gray pencil lines. The nose went down and the engine noise built to a roar as they swung on course and settled to a hundred-mile-an-hour cruise.
    THE STUFF SARK had read called it “power walking,” and the idea was to push yourself toward a speed of four miles an hour. That way your heartbeat was raised, which was the key to the aerobic benefit, but you avoided the impact damage to your shins and knees that you risked with proper jogging. It was a