The Informant!

Matt Damon plays a Vice President of a company that manufactures lysine, an
amino acid that gets fed to chickens to make them grow fast, and stuff. His
company is involved in price fixing, and he decides to inform on them to the
FBI, apparently out of a mix of conscience and enlightened self interest - i.e.
he fears it'll come out, and he'll be implicated. He proceeds to wear a wire
and gather evidence. The FBI builds a case, it all starts to go to court, and a
big price fixing scandal ensues.

However, unfortunately, as time goes on, it becomes clear that he's a bit
unreliable. And then a lot unreliable. And then actually completely nuts, and
the whole thing looks like it's going to blow up, fall apart, etc.

Now, this is all based on a true story, that of the Archer Daniels Midland
Company scandal. It's somewhat fictionalised, in order to play it for laughs.
Or, to be honest, smiles, smirks, and chuckles. It's not laugh out loud funny,
or edge of the seat dramatic. It gently meanders along, picking up momentum
slowly, losing momentum at times, but in generally, telling a satisfyingly odd
little tale.

Overall, I've seen two kinds of reviews of this film. Some of them tell you
it's a gently amusing little film that you should see, others who've said that
it's too slight, with the rewards not being worth the time invested in watching
it. I think that either viewpoint could be true, depending on taste. I was
certainly in the former camp, though.