Tightly plotted, expertly acted, Michael Clayton is a challenging, satisfying corporate thriller about a disillusioned lawyer forced to confront the compromises in his life. As brisk and ruthless as the attorneys it portrays, the film presents a vivid, seductive world in which power is inevitably tainted by corruption. It also offers George Clooney one of the most rewarding roles of his career.

Call him a fixer, janitor or bag man, Clooney's Michael Clayton is an expert at figuring out angles, calculating spreads and playing the margins for a Manhattan law firm. It's a career that's left the one-time public prosecutor divorced, heavily in debt and deeply cynical. The sheer incongruity of the latest crisis he's asked to handle—the meltdown of his friend and colleague Arthur Edens (Tom Wilkinson) during the final negotiations of a huge class-action lawsuit—is a warning sign that Clayton's own future is in jeopardy.

Edens had been defending a possibly carcinogenic weed killer sold by the U/North conglomerate. The more Clayton looks into the case, the more ambiguous his position becomes. Pressured by his boss Marty Bach (a smooth, persuasive Sydney Pollack) to keep Edens in line, Clayton is also being tested by Karen Crowder (Tilda Swinton), U/North's in-house counsel. Each new memo or business meeting raises the stakes higher, and makes it harder for Clayton to extricate himself from the enveloping mess.

With his three Bourne screenplays, Tony Gilroy has proven adept at building complex storylines from seemingly isolated moments that suddenly click into place. Just as important are his vivid characters, deep, complicated roles that give veterans like Wilkinson and Swinton the opportunity to show just how good they can be. The script for Michael Clayton works on several levels: as a snapshot of corporate life, a police procedural, an examination of schizophrenia, even as a tale of redemption. What's surprising is how well Gilroy, making his feature debut, has adjusted to directing. Despite a few loose ends that are nagging only in retrospect, the film is engrossing every step of the way. Robert Elswit's cinematography makes excellent use of backlighting, while the editing by Gilroy's brother John adroitly builds tension.

George Clooney has always had the potential to act this well, but previously has seemed reluctant to throw himself wholeheartedly into a role. There's no reserve or protective irony in his depiction of Clayton. It's not a flashy performance, but one grounded in a full understanding of his character's strengths and weaknesses. Watch how subtly he displays self-loathing as he fixes a car accident in the opening scenes, for example, or how he reacts to the taunting of an opponent in a card game. Clooney's work here matches any performance on screen this year.

Even with Clooney's star power, Michael Clayton may be a tough sell. Without a hint of romance, and very little humor, it is a tricky, demanding film with a harsh payoff. Let's hope there is still an audience for drama that is as serious as it is entertaining.