Breach is a film adapated from the story of O'Neill vs Hanssen. O'Neill is an FBI agent wannabe, given an assignment to watch every single step of Hanssen, an FBI senior agent. FBI believes Hanssen is a double-agent, working for the Soviet but there is no proof. They want to catch Hanssen red-handed, hence the need for constant surveillance. But the fact that Hanssen does so many useful things and goes to church every day casts a doubt to O'Neill. Can he accomplish that task?
Breach is a type of thriller that is quite rare nowadays. Granted, there is almost no puzzle to solve, the plot is pretty much predictable and likely not as cat-and-mouse as one would expect; but it is not polluted with unnecessary explosion-type actions. Sure, it would definitely bore Bourne's fans, but Breach just has different targets. Chris Cooper's performance (as Hannsen) is pretty convincing, he says more with his face and gestures than just his lines. He's supposed to be traitor, yet we can have a feel of his intimate plays running in his mind. Not that it matters, but I wouldn't hesitate to nominate him for an Oscar.
In short: Breach is too good to skip.