I’m always happy when a movie surprises me. These days it’s way too easy to learn everything there is to know about a film beforehand, so that when you finally get a chance to sit down and watch, nothing seems fresh. With the exception of a couple of previews, however, I came to The Informant! with no prior knowledge and therefore no preconceived notions. The end result was a delight.

The Informant! (don’t leave out the exclamation point!) is a docudrama about the illegal goings-on at biotech giant Archer Daniels Midland in the 1990s. It seems there’s this stuff called lysine, an essential amino acid that appears in a variety of foods, that can be synthesized via a complex process involving sugar — which can itself be derived from corn, though that’s another thing altogether — and added to animal feed. Feeds rich in lysine help cows and pigs grow big and fat, optimizing their suitability for slaughter and consumption. Given that lysine is such a big deal, millions upon millions of dollars are made from its manufacture and sale around the world. Imagine, then, if the global lysine producers colluded to fix the prices of the stuff and do a little optimizing of their own, cash-wise. That’s exactly what was going on.

The man who exposed all of this was Mark Whitacre, a relatively unassuming biochemist who headed up a division at ADM. He had a pretty comfortable life, a nice family and pretty much everything a career guy could want. The problem: he just couldn’t keep silent about this price-fixing thing. As a result, the FBI became involved and Whitacre became their prime informant.

At first blush, a story about price-fixing of a nutritional supplement you’ve probably never even heard of doesn’t seem like the most compelling material for a movie. You’d be right about that, actually. Price fixing turns out to be a pretty mundane affair, with various people holding meetings and agreeing to set prices at certain levels. Consequently, the real meat of The Informant! comes in the form of Mark Whitacre himself, and he is absolutely fascinating.

I don’t want to spoil the movie because I really do feel like you’ll get the best possible viewing experience coming into it cold like I did. In fact I’ve probably told you too much already, because the lysine price fixing doesn’t come into the story for about 20 minutes. During those 20 minutes we’re spending quality time with Whitacre and learning (we think) what kind of a guy he is.

Matt Damon is probably known best these days for playing Jason Bourne and therefore for being an action star. It’s easy to forget that he started off his career as a plainspoken actor doing actorly things. The Informant! will remind you that he has real talent not just for beating up bad guys and stabbing them with ballpoint pens, but for getting his teeth into a role and really going to town with it. Such is the case with Mark Whitacre, an extremely complex individual whose complexity only becomes apparent once you’re already deep into the film and absolutely fascinated.

The Informant! is also quite funny, not least because Damon does such a good job. Director Steven Soderbergh larded his cast with stand-up comics playing straight roles, but the humor comes primarily from the non-comedic actors. Matt Damon in particular is a hoot as Whitacre, not only because his character seems like such a bumbler, but for the strange, stream-of-consciousness ramblings we’re treated to in voiceover throughout the film. Scott Bakula, who doesn’t show up in very much these days, also shines as a perpetually harassed FBI agent who just wants to rein this deeply weird guy in long enough to make a case that sticks.

I saw this movie the same week I saw Jonah Hex (which I’ll review on Thursday). I came to both films totally unprepared for what I was about to receive. Jonah Hex was a nightmare, but I can’t overstate how much of a treat The Informant! really was. To give you an idea of how little I knew: I didn’t even realize Steve Soderbergh had directed the movie. Kind of a salient oversight, because Soderbergh is definitely behind much of what makes The Informant! such fun to watch. Most of the credit has to be given to the screenplay, which is top notch, but Soderbergh’s staging of the action is always a little off-kilter, always a little hyped up, so that it’s kind of like being in a constant state of over-caffeination. It makes you feel something like Whitacre himself, always jazzed by too much adrenaline, doing crazy stuff he never thought he’d be doing and for high stakes.

I won’t go so far as to say that The Informant! is educational, but I will say that I came away from with knowledge I didn’t have before. For one thing, lysine was something I’d only heard about through Jurassic Park, so having it turn out to be something you can get from eating eggs… good to know. I was also vaguely aware that Archer Daniels Midland was an enormous conglomerate that wasn’t always on the up and up, and The Informant! confirmed this. I don’t know if they’re as reprehensible as Monsanto, but as far as I know Monsanto hasn’t broken the law doing what it does. I’m willing to be corrected on that account, preferably by a funny, informative movie starring Matt Damon.

So if I haven’t made it abundantly clear yet, The Informant! is a movie you really should see. You will learn things you didn’t know about one of America’s largest companies, you’ll find out about a guy you’ve never heard of who did big things, you’ll get a laugh from the clever script, you’ll see Steven Soderbergh displaying an extremely light, comedic touch at the wheel of the whole thing and, probably most important of all, you’ll see Matt Damon doing something quite surprising. We should have known he could pull off a role like this, but that knowledge got lost along the way.