Martin Calvary is tired of the assassination game and wants out. But his employers give him one last job: to kill a diplomat in Prague. If he succeeds, he's free. If he fails, his past crimes will send him to prison for life. But the Czech mafia and Russian Intelligence are after his target too . . .
Robert Ludlum's Bourne series.
Gerald Seymour's At Close Quarters.
John Le Carre's Smiley's People.