There are two different storylines in "The Siege." One of them is interesting; the other isn't.

So guess which one dominates almost the entire second half of the film?

Granted, this suspense-thriller from "Courage Under Fire" filmmaker Ed Zwick has an intriguing and timely premise, one that attempts to deal with the issue of domestic terrorism. And the decision to focus on law-enforcement investigative procedures makes for an enthralling first half.

But things quickly bog down with heavy-handed rhetoric and convoluted conspiracies. And the sudden emphasis on action wastes the talents of a good cast (which includes Denzel Washington, Annette Bening and ace character actor Tony Shalhoub).

You'll notice, though, that that list doesn't include Bruce Willis, whose awful performance here detracts from the others and actually helps seal the picture's fate.

Washington stars as Anthony "Hub" Hubbard, who heads up the joint FBI/NYPD Terrorism Task Force. With his partner, Frank Haddad (Shalhoub), Hub investigates a bus hijacking, a tense situation that looks deadly but that results in a seemingly harmless prank. However, it actually turns out to be the first in a series of terrorist attacks, retaliatory strikes perpetrated by Arab-Americans who are protesting the kidnapping of one of their religious leaders.

With help from a CIA operative (Bening) who knows more than she's letting on, Hub discovers that there are a series of terrorist "cells" in New York that are responsible.

As bombings continue and the death toll rises, martial law is declared and Brooklyn becomes a police state under the rule of no-nonsense U.S. Army Gen. William Devereaux (Willis). Hub is appalled by the general's strongarm tactics and desperately tries to take out the final "cell" before things get even further out of hand.

To be fair, the first hour is riveting, with a couple of particularly tense scenes. But things go hideously awry from there as the ham-fisted messages begin to dominate. Zwick also throws in an unconvincing and unsatisfying conclusion.

It doesn't help that the focus changes from Washington's character and the even more interesting supporting players (Bening and Shalhoub) to Willis, who concentrates more on his trademark steely-eyed stare than on layered characterization.

"The Siege" is rated R for violent gunplay, profanity, gore, a scene of torture, use of some ethnic slurs, simulated sex (seen through surveillance devices), brief male nudity and use of one vulgar slang term.