Agent Provocateur, by Victor Ostrovsky

Espionage is a dangerous career. Lessons must be learned quickly—there are no second chances. One rule is this: never dirty the territory. That means no matter where you go everything must be left unchanged. You were never there. Any damage or destruction from an operation must appear to have "just happened." No signs of your involvement can be left behind. In Agent Provocateur, spies gather in a familiar setting—Times Square in New York. They are clustered for a reason—likely to cause damage. But will anyone ever know for sure?