Tense times call for tense movies. That's the way it was in the '70s, when government corruption and an unwanted war monopolized the headlines and inspired a decade's worth of politically astute heart-pounders.

After 9/11, however, Hollywood has been slow to catch on that conspiracy thrillers can be just as much goose-pimply fun as any horror movie.

But with "Michael Clayton," the genre that peaked after Watergate and Vietnam is back. And with a star like George Clooney on the case, a few more folks older than 21 may be tempted to go, too.

"I remember watching 'All the President's Men' and thinking how brilliant it was," says the actor. "We know everything that happens before we go in. And we still are on the edge of our seats. That requires really smart filmmaking."

His new feature, an eco-threat spin on paranoid cinema, just might be the kind of brainengaging popcorn that will be craved by moviegoers in a time of toys coated with lethal paint and contaminated spinach.

Clooney was drawn by the same nostalgia that drove him to direct and co-write 2005's "Good Night, and Good Luck," his paean to '50s media crusader Edward R. Murrow. He even turned down a salary to take the title role in "Clayton," which cost about $20 million to make — his usual payday for fluff like "Ocean's Thirteen."

The main attraction: a strong script.

That's where Tony Gilroy comes in. The screenwriter who helped reinvent the spy-guy adventure with the successful Jason Bourne trilogy also adds a director's cap to his career wardrobe with "Clayton."

Not that it was easy to pull off. He says at least five or so veteran directors, including Clooney and Sydney Pollack (who plays the actor's steely boss), tried to snatch his script away.

But Gilroy held on to his story of a "fixer" at a law firm, a morally compromised cleaner of legal messes whose life is about to hit bottom. At the same time, his company's conscience-struck top litigator, Arthur Edens (Tom Wilkinson), threatens to blow the whistle on an agrochemical client's shady dealings in a class-action suit.

Talk about suspense. Gilroy waited five years before a studio would let him direct "Clayton," a reluctance that was partly a result of the complexities of the genre.

"Thrillers like this are hard to finance," he says. "As the dollar amount of the budget rises, what disappears? The complexity disappears. The ambiguity disappears. The character disappears. The higher the budget, the more black and white the movie has to be."

And "Clayton," despite being in color, specializes in the shades of gray.

Take the random sights and sounds that hit the audience during the first five minutes. A manic Wilkinson narrates a rambling monologue over scenes of a near-empty office building as a copy machine cranks out pages. Pollack, working late, tells a reporter on the phone to buzz off. A panicky woman (Tilda Swinton) hides in a bathroom, drenched in sweat.

Elsewhere, a grim Clooney plays poker before tending to a rich sleazebag involved in a hit-and-run. The lawyer ends up on a dark road, where he pulls over and checks out a serene field with several horses.

Then, boom, his car blows up.

Words pop up on-screen: "Four days earlier." The film backtracks and fills in the blanks.

Such cold openings were a staple of the ambiguous '70s, but are rarities these days.

Says Clooney, who also has an executive-producer credit: "Studios have a difficult time with films like this. They are so terrified that if they don't keep things moving, you will get bored." But, as he learned while making the retro "Good Night, and Good Luck," "if you earn it, the audience will ride that out."