raitor, an absorbing and just a tad preposterous new thriller written and directed by Jeffrey Nachmanoff, manages to present an updated rendition on a classic formula by turning a police procedural into a terrorist procedural. It also offers up one of the more gratifyingly complex lead characters seen in movies of late.

The story begins with a quick prologue in 1978 Sudan, with a boy who witnesses a car bombing. Quickly, we’re whisked into present-day Yemen, and that Sudanese boy has become a man shaped by violence. Played by Don Cheadle ("Hotel Rwanda," "Crash"), that man is a Sudanese-born former U.S. Special Forces soldier named Samir Horn.

Horn has been arrested in Yemen for attempting to sell explosives to an Islamic terror organization. While imprisoned, he befriends and gains the trust of terrorist named Omar (Saïd Taghmaoui), who helps him escape. When his colleagues arrange a jailbreak, Omar brings along Horn and his extensive knowledge of blowing stuff up. In that American way, he's just a guy doing what he's got to do.

Soon, Samir is planning bombings, one of which he carries out himself, at the American Embassy in Nice, France. Two FBI agents are trying to prevent that from happening. Agent Archer (Neal McDonough) is the dead-eyed hard case of the "kill them all" school. His partner, Agent Clayton (Guy Pearce), is the son of a preacher and studied Arabic cultures in college, and he is the role model for the movie’s "fair and balanced" views. Horn travels to Italy, France, Canada and America, doing the bidding of his new friends -- building bombs and teaching others to use them. But, Clayton is always a step or two behind him.

Traitor holds your attention and it is hard not to take it seriously.

There are some scenes that groan with half-digested themes, but Mr. Cheadle’s performance gives “Traitor” a sense of ethical gravity and real intrigue. That's no surprise; he's a fantastic actor. His Samir is mysterious precisely because he seems, at every turn, utterly sincere, honest even at his moments of greatest duplicity.

The story, by Yet Nachmanoff and Steve Martin - yes, the wild-and-crazy Steve Martin - is gripping and interestingly plotted. Amid the bombings and prison breaks, the story moves around a lot — from Yemen to Canada, from Chicago to Marseille — and involves a lot of interesting minor characters- among them Jeff Daniels as a sneaky Capitol Hill pol and Aly Khan as a Saville Row jihadist.

But at its best the movie feels less like the usual rushed, contrived action-travelogue than a valiant effort to untangle some of the moral complexities of the post-9/11 world.