A majority of the humor in Steven Soderbergh’s corporate espionage comedy The Informant! comes from watching the protagonist, the vice president of a prominent agricultural-industry giant, issue a series of internal non sequiturs while inadvertently gabbing his way right into his own grave -- and Matt Damon’s mouth is a virtual earth excavator. Sporting a haircut that’s spritzed to early-'90s perfection and neckties that look like a bad '80s hangover, his incessant, increasingly delusional ramblings provide the film with some of its most outlandishly funny moments. That is, of course, until his entire ruse begins to unravel and we’re struck with the sudden realization that we’ve been laughing at a man with a serious mental illness. At that point, the comedy turns quasi-tragic. Then again, if the character doesn’t take his condition seriously, why should we? Mark Whitacre (Damon) is a high-level executive at Archer Daniels Midland (ADM), an agricultural company that uses corn to turn a tidy profit. But something fishy is going on behind the scenes at ADM, and it’s beginning to draw the attention of Uncle Sam. Before long, Whitacre is bitten by the whistleblower bug, and decides to turn informant for the FBI. Though special agents Brian Shepard (Scott Bakula) and Bob Herndon (Joel McHale) are elated to find an inside man who’s willing to give up the goods on ADM, they quickly discover that they’ve gotten more than they bargained for when Whitacre develops an acute case of verbal diarrhea. Not only that, but the details seem to change every time Whitacre opens his mouth, placing his contacts in the Bureau in a rather precarious position and ensuring that he’ll never realize his aspirations of running the company. Before long, Whitacre has become so enamored of his role as government informant that he can no longer sort fact from fiction in his own mind, and fails to realize that price fixing at ADM is the least of his worries. Reflecting on Soderbergh’s career, The Informant! can almost be taken as the comic inverse of Erin Brockovich; whereas the gorgeous crusader in that film successfully used her quick wit and good looks to take down a corporate monster, the rambling, bipolar knight erroneous here can’t help but drop his sword on his foot every time he raises it. Alas, unlike the uncompromised Brockovich, Whitacre has been complicit in the wrongdoings of the company he now seeks to expose, only he’s too lost in his own head to realize it. From Whitacre’s distorted perspective, the FBI should hail him as a hero for his efforts in ripping the lid off of corporate malfeasance, but from an objective standpoint he’s just as guilty as the rest of the well-dressed criminals he seeks to take down. As a result, our instinct is to laugh as the dirt begins to pile up around Whitacre’s ankles, and screenwriter Scott Burns peppers his screenplay with enough hilarious moments to maintain our good will even when the story begins to drag on a bit longer than necessary. The same goes for Marvin Hamlisch’s playful, upbeat score -- one of the most distinctive in some time, thanks to a retro-kitsch arrangement that evokes both James Bond and Austin Powers with its familiar spy guitar twang and creative use of kazoos. Hamlisch’s idiosyncratic compositions make the occasional lag time between laughs breeze by, and provide the oddball protagonist with the perfect marching music. Still, the majority of credit for the film’s overall success goes without question to Damon. The Informant! is the kind of film that could have easily faltered with a lesser actor in the lead, yet Damon’s farcical tour de force of a performance is compulsively and consistently watchable thanks to the endearing nuance he brings to the role. His character is just so warped that it’s impossible not to like him, even when you want to wring his neck for being such an insufferable dolt. Kudos also go out to casting director Carmen Cuba for assembling a fantastic team of supporting players to orbit around Damon’s weirdo gravitational pull. Without them, the lead character’s fascinating quirks wouldn’t shine nearly as brightly as they do.