“Let’s take a ride,” said Frank. He strode out of his office toward the elevators, grasping me by the elbow and pushing me before him like a shopping cart. When we reached the basement parking garage, he steered me toward an old Chevy Impala, opened the door and told me to get in. He drove a few miles to Tysons Corner Mall, the largest shopping mall in the region, and parked in front of Nordstrom’s department store.

“Here’s the drill, son,” he said. “In this shopping mall there are five people who have been assigned to tail you. Your assignment is to identify any three of them. If you do it, you get to have lunch. If you fail, no lunch. Tough shit. And don’t try to cheat on me by chowing down in the mall. Is that clear?”

“But how am I going to know who’s tailing me? I don’t have a clue how I’m supposed to do this.”

“Good boy! When you don’t know something, always ask questions. Now there’s three types of surveillance. There’s your loose tail, where you’re following the target from a distance; there’s your close tail, when it’s essential not to lose the target, so you run some risk of detection; and there’s your rough tail, where you don’t care if the target knows you’re following him. To make it easier, the five folks following you have been instructed to maintain a close tail. So you have a chance of catching them.

“Now, on a surveillance-detection run—which is what this—you want to look for the odd man out. The person who speeds up when you do and slows down when you do, even though everybody else is walking at normal speed. Or the person who follows you outside when everybody else is going inside. Or the person you saw in Nordstrom’s, and then in Crown Books, and isn’t it a coincidence he’s now in the doggie hair salon, too? Am I right?”

“You’re right. Look for the odd man out.”