This espionage novel is one of Ian Rankin's early books, written before he started the John Rebus detective series. In this story, Miles Flint is a British spy, a "watchman" who surveils individuals suspected of illegal/terorist activity in London. While watching an Arab suspect in a hotel lobby Flint gets distracted by a beautiful woman; the suspect - an assassin - gets away and kills an Israeli man.
Flint thinks the woman was sent purposely and starts to look into the incident. Soon afterward, having trouble at home, Flint spends a few nights in a residence where fellow British agents are spying on suspected Irish terrorists. This surveillance is called off prematurely and Flint starts to think something isn't kosher in his spy agency.
Next thing you know Flint is sent to northern Ireland on assignment and things go badly wrong. His suspicions confirmed, Flint sets out to uncover the dirty secrets people are trying to hide. There are a lot of similar characters in this story and you have to pay close attention to remember who's who. Not as good as the Rebus books but it's an okay espionage novel.