The Democratic Terrorist (1992)

Hamilton is assigned to infiltrate a terrorist group in West Germany, a part of the Red Army Faction (RAF), that supposedly are planning an operation in Sweden. Hamilton is chosen because of his background in the leftist movement. As a member of the group, he takes part in bank robberies — the preferred way of the RAF to finance their operations. In the end, when all terrorists are in one place, he leads the German Counter-terrorism unit GSG 9 to the location. Description above from the Wikipedia article Carl Hamilton novels, licensed under CC-BY-SA, full list of contributors on Wikipedia.