Unlike the re telling of Tinker Tailor Soldier Spy, Le Carres A Most Wanted Man pares the book back to its essentials holding the audience taut right up until the unexpected ending. Phillip Seymour Hoffman in one of his last roles is mesmerising as the washed up Gunter Bachmann who runs a small counter terrorism unit in Hamburg  whilst managing internal agency rivalry, the CIA and the German constitution!
Bachmann’s interest is piqued by the arrival in Hamburg of a Chechen Russian seeking asylum. Unfortunately Issa Karpov underplayed masterfully by Grigoriy Dobrygin  is on the run having been imprisoned and tortured by the Russians. Karpov comes to the attention of the authorities after being taken in by a Turkish German Muslim family. Once his background is revealed the proper authorities want him snuffed out to prevent another 9/11 noting Mohammed Atta planned the attacks from Hamburg.
Rather than arresting Karpov outright Bachmann wishes to use him as a pawn to snare and turn a successful businessman and philanthropist with Islamic ties. Due to internal rivalries the best he can do is play for time and act as quickly as he can. Which he does with scant regard for the rules.
Using less than ethical tactics he enrols Karpov’s human rights lawyer played by Rachel McAdams into the cause. She acts as the go-between for Bachmann and Karpov and has her idealism manipulated to the point she signs on for the happy ending. Much of the movie is in fact seen through her eyes and reactions.
But spying especially in this day and age doesn’t have a happy ending. And neither does A Most Wanted Man.