Directed by Soderbergh, starring Matt Damon.
Based on a true story, this is a tale of epic, pathological liar-fail and makes you cringe in your seat as Mark Whitacre (Damon) just cannot stop lying. I think Damon is brilliant - when you see him in this movie, where his character is far removed from the assassin in the Bourne movies (although in Informant he revels in the fact that he is 'undercover' for the FBI), you get an idea of Damon's acting abilities.
Whitacre is a chemist brought into the business admin of a large corporation that manufactures food and feed additives. Eventually he becomes a whistle-blower, but his story is filled with so many lies, that you don't know where to start and what to trust in what he says. Also struggling with a bipolar disorder, it all eventually leads to a meltdown against which he still tries to resist through lying/delusion.
Check it.