American Fable is ambitious, maybe too much so sometimes, but there's an intense pleasure in the boldness of the film's style.
Belfast, 1988. The height of the Troubles. British troops occupy the city and are at war with the Irish Republican Army. The British want to retain Northern Ireland as part of the United Kingdom. The IRA considers them invaders. Martin McGartland doesn’t much care.
Like many young criminals, he is devoutly non-political. He’s a two-bit hustler, stealing and reselling clothing or whatever else he can move. A wise guy, he moves confidently on the mean streets. McGartland (Jim Sturgess) doesn’t like the British, but when the IRA breaks his friend’s legs with a baseball bat, he likes that even less.
He’s recruited by Fergus (Ben Kingsley), an officer in the Special Branch of the British police, to become a double agent, an informer. Fergus has noticed how he moves through Belfast, known to the IRA, unintimidated by the British troops. Both sides already think they know who he is.
Informing on the IRA was of course a nearly certain death sentence. It seems incredible that anyone would take such a risk, and very few did. McGartland’s information is credited with saving the lives of at least 50 men, and you’d think the IRA might have noticed parallels between their assassination operations and McGartland’s participation, but apparently not. Only at the end of the film is there a situation where his role will be betrayed, and by then, he already realizes that he will be living for the rest of his life in hiding.