Breach tells the true story of the FBI's investigation and capture of Robert Hanssen, the most damaging mole in the Bureau's history. I don't know that much about Hanssen, so I'm not sure how true it is or how many liberties they take, but Eric O'Neill, the actual would-be agent who was assigned to get close to him as his assistant (played here by Ryan Philippe) is credited as a technical advisor on the movie, so that would seem to lend at least some credibility.
Aalthough it pays lip service to the conventions of the spy movie (the realistic spy movie, that is), Breach is more of a character study about a man who chooses to spy than a thriller. And Hanssen proves an absolutely fascinating character to study, especially in the capable hands of Chris Cooper, who has by this point appeared in so many spy movies that he's almost a "convention of the genre" unto himself! Luckily, he's also one of America's finest actors, and he turns in a tour-de-force performance as Hanssen. It's the kind of performance that, had this movie come out two months ago instead of now, would have generated plentiful Oscar buzz. As it stands, though, it will be long-forgotten by next year's awards season, as are all movies that come out
Hanssen is a man of deep, seemingly contradictory convictions. He's deeply religious (which factors heavily in the film), yet also what Laura Linney's character calls "a sexual deviant" with an unhealthy obsession with Catherine Zeta Jones. He's a jerk and a chauvinist, yet he seems to deeply love his wife and family. And he's fiercely patriotic with strong right wing political views--yet he spied for Communist Russia!
Cooper manages to pull off these contradictions mainly because he convinces us that Hanssen, above all else, is smart. "He's smarter than all of us," Linney confesses, and we believe it because we see it in Cooper's eyes. O'Neill sees it too, and comes to respect him as a mentor before being clued in to the full extent of his nefarious activities.
I've never been a huge fan of Philippe's, but he does a good job with his part, particularly once his character realizes where he stands, and is forced to constantly outwit a naturally suspicious boss who's not only smarter than him, but more cunning, dangerous, and ultimately unbalanced. At this point the movie veers into Silence of the Lambs territory, telling the story of a young FBI agent (or hopeful agent) being drawn in by a dangerous, sociopathic mentor while trying desperately to maintain his distance. Like Clarice Starling, O'Neill reveals too much of himself to his learned adversary, and soon Hanssen is playing Hell with his personal life, causing O'Neill to question what he believes in and his wife (abley played by Wonderfalls' Caroline Dhavernas) to question their marriage.
The relationship between Hanssen and O'Neill forms the core of the movie, culminating in a tense, crucial scene in which O'Neill has to convince a drunk, armed Hanssen that he can still trust him. The approach he takes is surprising and revealing: rather than piling more lies upon lies, he tells the truth. (Or most of it.) The scene demands great performances from both actors, and Philippe actually holds his own nicely with Cooper.
Ultimately, Breach doesn't offer an explanation from Hanssen. The closest he comes is in speculating to his arresting agent (24's Dennis Haysbert--and no, that's not a spoiler; the movie begins after Hanssen has already been caught and then flashes back) on why notorious CIA traitor Aldrich Ames may have betrayed his country. His speculation is certainly telling, but far from definitive. Cooper crafts such a believable enigma that we don't expect that kind of revelation from the character, and were it to happen it would cheapen the movie and the performance. The performance is so strong that it tells us everything we need to know about the character, and Breach doesn't require any tacky, last minute exposition.