HBO's loose-nukes docudrama is much too subtle.

Just in case 9/11 and  The Sum of All Fears hadn't jolted Americans into paying attention to the nightmare of nuclear terrorism, HBO has weighed in with Last Best Chance, which debuts tonight at 8 p.m. ET.

The poorly titled and very poorly acted hour-long warning-slash-docudrama about the free world on the brink of vaporization stars former Sen. Fred Thompson, R-Tenn., as (presumably) the last president of the United States. Three terrorist cells steal a nuclear warhead or the ingredients needed to make a nuclear warhead. Government officials from Washington to Moscow learn of the impending attacks, but, in the end, they are unable to prevent the terrorists from entering the United States and Britain, where (apparently) Armageddon lurks.

Alas, Last Best Chance is, one hopes, neither our last nor our best chance of alerting the public to the possibility of mass death at the hands of atom-bomb-toting terrorists.

It's not that the movie is off the mark. It's right on target. As former Sen. Sam Nunn, D-Ga., who took part in a panel after an advance screening last week at Washington's Four Seasons Hotel, pointed out, it's only a matter of time before something truly unthinkable happens in New York, London, or Paris.

The problem is that stirring the American public from its slumber requires bloodshed. It requires violence. Recall that it took Schindler's List—with its ghoulish depiction of little Jewish girls and boys being led to the crematoria—to spawn a mini-movement of Holocaust studies. Similarly, had it not been for the first 40 minutes of Saving Private Ryan, there probably wouldn't be a World War II memorial on the Washington Mall today.

Last Best Chance, by contrast, is a tad too literary. Consider the final frame: An SUV—framed by deciduous trees and an American flag, bathed in a lovely, upstate New York kind of chiaroscuro—pulls away from a guard post at the U.S.-Canadian border. Inside the SUV are two white people who look nothing like the people who usually blow up embassies and skyscrapers. Sitting in the back seat is a bomb in an unmarked crate destined for Manhattan … And then? Then nothing: We never get to see what happens when the bomb goes off. We only get to imagine it.

And therein lies the crux of the problem. Americans have lost their taste for imagination. Television, movies, the Internet—mass culture—doesn't allow for much imagination nowadays. The height of hip is revelation: To show everything (sex, death, various species of self-degradation) is to be bold, ahead of one's time, even "courageous."

Senior policy wonks, think-tank analysts, and Homeland Security higher-ups may prefer John Le Carré to Robert Ludlum, but the public demands Kalashnikovs, roadside bombs, and flying limbs.

True, there's that gun battle toward the beginning of the movie at the top-secret facility in the Belarusian hinterlands. But only one hapless guard gets killed. And he was just an extra; no one will shed any tears for him. Most of the pivotal scenes in Last Best Chance take place in the Oval Office and involve telephone conversations between Thompson's President Ross and the Russian president who always seems to be in his pajamas. Viewers of The West Wing may find this compelling; the other 280 million people in the United States will wonder when the action starts.

This movie is not about action. It's not about what you see. It's about what goes unseen. It's about the quiet evil of invisible, protean forces slithering through porous ports and borders. It's about nuance.