Jack Reacher, 13

SUICIDE BOMBERS ARE EASY TO SPOT. THEY GIVE OUT ALL kinds of tell-tale signs. Mostly because they’re nervous. By definition they’re all first-timers.

Israeli counterintelligence wrote the defensive playbook. They told us what to look for. They used pragmatic observation and psychological insight and came up with a list of behavioural indicators. I learned the list from an Israeli army captain twenty years ago. He swore by it. Therefore I swore by it too, because at the time I was on three weeks’ detached duty mostly about a yard from his shoulder, in Israel itself, in Jerusalem, on the West Bank, in the Lebanon, sometimes in Syria, sometimes in Jordan, in buses, in stores, on crowded sidewalks. I kept my eyes moving and my mind running free down the bullet points.

Twenty years later I still know the list. And my eyes still move. Pure habit. From another bunch of guys I learned another mantra: Look, don’t see, listen, don’t hear. The more you engage, the longer you survive.

The list is twelve points long if you’re looking at a male suspect. Eleven, if you’re looking at a woman. The difference is a fresh shave. Male bombers take off their beards. It helps them blend in. Makes them less suspicious. The result is paler skin on the lower half of the face. No recent exposure to the sun.

But I wasn’t interested in shaves.

I was working on the eleven-point list.

I was looking at a woman.

I was riding the subway, in New York City. The 6 train, the Lexington Avenue local, heading uptown, two o’clock in the morning. I had gotten on at Bleecker Street from the south end of the platform into a car that was empty except for five people. Subway cars feel small and intimate when they’re full.