Michael Clayton works as a lawyer at one of New York's biggest law firms. He's 45 but is never going to be a partner. Instead he's everybody's fixer. He can get a client's charges reduced or dropped, he can deal with hit-and-run clients; partners call him with their worst messes. Early on, one of the clients says, truculently, "I thought you were a miracle worker." "I'm a janitor," he replies. In a way he's like Harvey Keitel's Wolf in "Pulp Fiction." Michael is played by George Clooney, in a lovely performance, wearing his lawyerly suit and tie, always on his cell phone, working through his weariness at his work. He's addicted to playing in high-stakes poker games, and in fact, trying to get something for himself, he opened a bar with his alcoholic brother that's just gone under and he now owes $75,000 to the shysters. He's divorced but takes his son to school in the morning and sees him every Saturday.

The firm's biggest client is an international agricultural giant named UNorth (think Monsanto or Con Agra). For the last six years they've been defending a $3 billion-dollar class-action suit by the survivors of the cancer that UNorth has managed to spread on their farms with its weed-killer.

And then one of the firm's partners, Arthur Edens (Tom Wilkinson), who's been leading UNorth's defense, goes crazy during a Milwaukee deposition. He strips and runs through the parking lot, naked in the snow. He hasn't been taking his medications. But it isn't that; he's discovered the smoking gun that if revealed will ensure UNorth's losing the case, Michael's firm losing UNorth as a client, and Edens losing any claim to being a moral person.

As Michael sorts all of this out, he comes up against the dragon lady, the general counsel to UNorth, Karen Crowder - played by that remarkable actress Tilda Swinton - who is cool and articulate, but whom we also see in a montage by director Tony Gilroy rehearsing her lines as she gets dressed in her power suit with an unobtrusive string of pearls; like any formidable opponent she puts her pantyhose on one leg at a time, you might say, but what we also see is what goes into a corporate defense. It's not a pretty sight.

This is the first film Gilroy has directed, but as a writer he's written "The Devil's Advocate," the three Bourne films starring Matt Damon, and others. He has a great director of photography, Robert Elswit ("Boogie Nights," "Good Night, and Good Luck," "Syriana"), and they have chosen to reduce their color palate to moody blues and greens, though there is a lovely shot of Michael on a hillside at dawn that's crucial to the plot.

"Michael Clayton" is another example of how smart George Clooney is in choosing his projects. He has the looks and the magnetism of the great screen actors, and he cannot change that, but he knows how to play against them when that's required. If he isn't already the iconic presence of today's films, he surely will be before his career is over.