While not especially clever or creative, "The Siege," an action-drama about the Constitutional implications of a military takeover of New York City in the wake of terrorist bombings, grabs the audience by the intellect and doesn't let go for 120 minutes.

The story arch is so predictable that by the third reel it's readily obvious one of the leads -- Denzel Washington, the conflicted FBI Boy Scout; Annette Bening, an elusive CIA spook; or Bruce Willis, the duty-blinded Army General -- is doomed to not finish the picture.

But while the plot follows an outline format handed out on the first day of Scriptwriting 101, director Edward Zwick (who co-wrote the movie) plays all the right angles of this ultra-realistic story to keep it tense and provocative, deftly tapping that on-the-edge-of-your-chair feeling we all get while glued to CNN during large-scale crises like Oklahoma City and Tienman Square.

At the center of "The Siege" is a three-headed hydra of American anti-terrorist efforts -- the antagonistic, distrustful relationship between the FBI, the CIA and the military.

When Islamic extremist suicide bombers blow up a packed NYC bus and a Broadway playhouse, a power struggle erupts, and that goes beyond simple inter-agency rivalry. Not only do our heroes and anti-heroes conceal information from each other, but they do so with malice aforethought.

An early hostage scene is racked with tension because Bening has information about the perpetrators that she refuses to share with Washington, who is trying to negotiate a surrender. The bus blows up, scattering debris all over a Brooklyn street in slow-motion and sending pangs of guilt and animosity coursing through Denzel's veins.

He finds his investigation hindered by Bening's meddling on bahalf of the CIA, which is busy protecting its own interests. A veteran liar with the weight of her personal investment in Middle East black ops chiseled on her weary face, she never gives a single straight answer in the course of the movie (out of habit as much as anything else), which quickly builds a palpable strife between herself and Washington's by-the-book Fed.

But before long both agencies are hog-tied by the military, which moves into the boroughs with tanks and troops after continued attacks beget a reluctant martial law order from the White House.

Bruce Willis is smartly cast as a career war hawk who lobbies strongly against using the military in an American city, but once the dice are rolled, fulfills his duty with a practiced bent.

Washington has much the same role he played in "Crimson Tide" -- the intelligent, stalwart idealist who defiantly challenges Willis' judgment as immigrant Arabs and Muslims are corralled into internment camps, many to be ruthlessly interrogated for no more reason than fitting a suspect profile.

This twist to the story is what elevates "The Siege" beyond its action roots to the level of a political thriller. Some Arab-American groups have protested the film's use of Islamic baddies, but Zwick shifts skillfully between the hunt for terrorists and a message-minded focus on the morality of reactionism and its effect on freedom and tolerance, as Washington and Bening skeptically team up to try to end the violence before the Army gets carried away.

Although his point is obvious, Zwick (whose synchronicity with Washington is as apparent here as it was in "Courage Under Fire" and "Glory") works subtly on other levels -- for instance, picking locations with cold, autocratic, Iron Curtain-esque architecture to hint at the potentiality of such a military presence. Even the presence of a token good guy Arab -- Denzel's partner played with brilliant conviction by Tony Shalhoub ("Big Night," "Men in Black") -- doesn't feel forced.

The director is also careful not to give "The Siege" too much of an action movie air, keeping the on-screen explosions to a minimum and finding other ways to dramatize the terror. In one resourceful scene, Washington is conducting a meeting of federal agency brass when suddenly a wave of beepers and cell phones go off in the room, a dramatic indicator of another attack and the significance of its impact.

"The Siege" has several weaknesses, not the least of which is that the terrorists' entry into the U.S. is predicated on an far-fetched twist in the story -- that one strong and ruthless character could be blinded by emotion.

There's also a couple silly oversights, like when Denzel goes into a terrorist den "undercover," as if his suspects wouldn't recognize him after being all over the television for a week giving the press briefings about the investigation.

But while there's no Oscar material here, "The Siege" a strong political thriller that adeptly projects internal dangers that very well could arise if terrorists ever did penetrate America on a large scale. Potent and thought-provoking stuff.