"Argo," which re-enacts one of the most dramatic tales of the tense Iranian Hostage Crisis, is at times an utterly gripping film. That's a genuine accomplishment for a movie based on real events whose conclusion we already know.

But there are too many problems to say that Ben Affleck's third film is as good as his first two. Affleck has more talent as a director than most actors who take a turn behind the camera. "Gone Baby Gone" and "The Town" were well-crafted pieces of work that indicated their director had a definite, unmistakable point of view. With "Argo," unfortunately, what was an asset has become an albatross.

It's 1979, and the U.S. embassy in Tehran is under siege. Affleck recreates a frightening scene. The tension is palpable even inside the building, which angry Iranian students have not yet breached. "They need an hour to burn the classified," one staffer says, hoping the mob can be held off that long. It's not just details of American support of the now-exiled shah that must be destroyed. Any Iranian discovered to have aided Americans -- or just requested a visa to move to the U.S. -- is in danger.

On screen
2 out of 4 stars
Stars: Ben Affleck, Bryan Cranston, John Goodman
Director: Ben Affleck
Rated: R for language and some violent images
Running time: 120 minutes

The embassy is eventually taken, but half a dozen staffers manage to escape through a back door. They finally find refuge at the residence of the Canadian ambassador. But they need to get out of the country before they're discovered by the Revolutionary Guards, who have taken over Iran.

Enter Tony Mendez (Affleck). This CIA officer specializes in getting people out of tight situations. He's never had a failed mission. But this one is trickier than most. There aren't any Canadians left floating around the riotous country for the six Americans to pretend to be. So Tony thinks of a reason the group might enter Iran -- they're writers, directors and other filmmakers scouting exotic locations for a science-fiction film.

Not even Hollywood could have come up with such a daffy plot -- it actually happened. The real Tony Mendez had a good friend in the film industry, John Chambers (John Goodman), a makeup artist who received an honorary Oscar for his work on "Planet of the Apes." They set up a fake production company, with the help of an insider who knows how Hollywood works.

"Argo" switches between two very different tones and does it very well: The action is exciting, the Hollywood scenes are dryly funny. But we never get to know the people for whom this farcical plot has been invented. The six trapped Americans, worried for their lives, are little more than anonymous paper-pushers. Yet Mendez risks his life for them, and others their careers.

The reason for the predicament is also left opaque. A prologue at the beginning of "Argo" details the shah's bad deeds, implying the revolution was a popular uprising against an unrepentant tyrant. That's not anything like the full story. "Argo" aims to reveal the little-known details of one of America's proudest moments. But it seems to suppress far more than it exposes.