Writer-director Tony Gilroy’s legal thriller moves so skillfully through a carefully-designed thicket of apparent complexities that it may take you a while to realize how simple and conventional a story it’s actually telling. And George Clooney is so smoothly charismatic in the title role of “Michael Clayton” that his leading-man power may blind you to the fact that his character is really a terribly familiar one. The picture is essentially yet another tale of unmasking corporate skullduggery via the courts (and extra-legal tricks) combined with a plot about the redemption of a torn and troubled man—“Erin Brockovich” meets “The Verdict,” so to speak. The fact that it’s as entertaining as it is, is a tribute to the dexterity of the execution.

Clayton is the “fixer” in the big New York law firm of Kenner, Bach & Ledeen, cleaning up clients’ emergencies as quickly—if sometimes underhandedly—as he can, and increasingly unhappy with his role as what he describes as a glorified janitor. He’s also facing financial problems—a restaurant he’d sunk his savings into has gone belly up—and family difficulties: his druggie brother (David Lansbury) was the one who doomed the restaurant, and he’s struggling to maintain contact with his precocious little son (Austin Williams), who lives with his ex-wife and her new husband.

It’s in the midst of such troubles that he’s saddled with a major job by his boss Marty Bach (Sydney Pollack): to deal with the firm’s top litigator Arthur Edens (Tom Wilkinson), who’s literally gone bonkers while preparing to defend the huge conglomerate U/North in a suit charging it with having poisoned untold numbers of people with its agricultural products. As Michael tries to get a handle on the situation while dealing with his own monetary and domestic crises, he comes to realize that Arthur may be involved in helping one of the defendants, a physically damaged young woman named Anna (Merritt Wever) to expose the company’s wrongdoing rather than protecting the client’s interests. As if that weren’t bad enough, it’s all happening at a time when Marty’s putting the final touches to a lucrative merger of the firm that could be doomed by bad publicity.

Interspersed with Clayton’s side of the story are scenes of U/North’s chief counsel Karen Crowder (Tilda Swinton), who’s overseeing two fixers of her own (Dennis O’Hare and Robert Prescott) in her desperate efforts to succeed as well at crisis control as her predecessor and mentor Don Jeffries (Ken Howard). The two plot lines aren’t just juggled throughout, but are themselves shuffled chronologically—the movie is actually a long flashback—to make events more shadowy and opaque. The result is that “Michael Clayton” winds up being a lot more mystifying than it really has any right to be, given that it’s actually just another tale of a company attempting to cover its unsavory tracks and of an unlikely hero finding a renewed sense of purpose to bring them down. To be sure, the script does add another layer to the mix by inserting the Edens character, whose crusade Clayton must decide whether or not to take up. But in the end, though he’s well—if very flamboyantly—played by Wilkinson, that character is more narrative flourish than essential element; one can easily imagine the story being constructed just about as tightly without him.

Still, for all its artificial sleight of hand, the picture succeeds in holding our interest, up to and including a final face-down that’s a bit silly (and doesn’t tie up all the loose ends) but is still fairly satisfying. A good deal of the credit is due to Clooney, who constructs a rich portrait of a conflicted man while effortlessly winning our sympathy for the character. On the other hand, Swinton, an excellent actress, struggles with the role of Crowder, who’s presented as a woman terrified that she might not have the strength to do her job and overplays the character’s nervousness. Most of the supporting cast, including young Williams and Sean Cullen as Michael’s cop brother, contribute nice turns. The strongest support, though, is offered by Pollack, who once again (as in “Tootsie,” “Eyes Wide Shut” and several other movies) plays himself, but does so engagingly.

The craftsmanship in “Michael Clayton” is on a very high level, with elegant cinematography by Robert Elswit that uses an understated palette of colors very effectively and a properly moody score by James Newton Howard. Their contributions, like the acting, can’t entirely hide the fact that there’s a good deal less to the movie than meets the eye—and the ear. But there’s still just enough to make for a close verdict in its favor.