He earned a better than decent salary, approaching $175,000 with Senior Executive Service and SAIC—Special Agent in Charge of detail—pay factored in, but didn't seem to live up to his means. He was right up to the minute in terms of using his fairly generous allotment of vacation time, but as far as she could tell, he had never taken a day of sick time. Never.

As part of her training, Alison had taken courses in single and team surveillance. Keep slightly to the right of the car ahead. No sudden lane changes. Anticipate the moves of the quarry, and be ready to react smoothly. Employing every rule she could remember, she followed Griswold across the Potomac and onto I-95 leading south into Virginia. On paper, and indeed in real life, Treat Griswold seemed almost too good to be true. To this point, in addition to his not being among the most physically attractive men in the world, the only chink in his highly polished armor seemed to be the inhaler he carried in breach of regulations, or at least in violation of tradition and unwritten protocol.

The likely explanation, hardly a thrilling one, was that the president had simply found it more convenient to do things that way, rather than having to scout down the doctor on duty each time he felt wheezy while away from the medicine cabinet in the official residence.

Griswold was driving in no particular hurry, but now, for the first time, something curious had happened. He had passed the exit to Dale City and was continuing south on the interstate. Alison pulled her road map up and smoothed it open over the steering wheel. There was no doubt about it. Griswold wasn't headed home. Five miles . . . ten . . . twenty. . . .

Alison fished two sticks of bubble gum–flavored Trident from her purse and began working them over with vigor. She had been a serious gum chewer since grammar school, having made her way from Fleers Dubble Bubble, through Juicy Fruit, to Wrigley's Spearmint, and finally to Trident sugar-free, with an occasional jawbreaker thrown in. It wasn't the most attractive habit in the world, she knew, but she was hooked. Over the years, she had come to chew mostly when she was tense, and like a ventriloquist of sorts, she had mastered the art of chewing, when she had to, without visibly moving her jaws.

They were entering Fredericksburg when Griswold eased off the highway. Alison slowed and managed to keep a car between them, but the situation was getting dicey. Still, there was no hint from ahead that she had been spotted. She risked dropping back half a block.