In theaters

K-19: THE WIDOWMAKER. Directed by Kathryn Bigelow, written by Christopher Kyle, 138 minutes, rated PG-13.

Kathryn Bigelow’s submarine thriller, “K-19: The Widowmaker,” is set in 1961 – one of the hottest points of the Cold War – a time when the Soviet Union and the United States were in such a bitter nuclear showdown, the world could have ended at any moment in a sudden bouquet of mushroom clouds.

As the film opens, audiences are given this information in a series of title cards drummed onto the screen with the considerable heft of Klaus Badelt’s masculine score. They’re told that the film is about the first Soviet submarine to carry nuclear weapons and that the story behind the film is based on true events, a period in history kept so secret by the Soviet government, it took 28 years – and the collapse of the Soviet Union – before those who lived through it could make it public.

Why the embarrassed silence? Apparently, the Soviets didn’t want the world to know that they’d hammered together a great clunker of a submarine, an untested bucket of bolts that was such a jokeavitch, it’s no stretch to say that it was a sinking coffin.

In spite of this intriguing opening – and the formidable presence of Harrison Ford as the K-19’s new captain, Alexei Vostrikov, and of Liam Neeson as the sub’s former captain and now second-in-command, Mikhail Polenin – the film runs shallow alongside such submarine classics as “Run Silent, Run Deep” and “Das Boot.”

The problem is that Bigelow, while effectively capturing the claustrophobia inherent within a submarine, only occasionally realizes the drama within the film’s premise: Vostrikov’s mission is to take the sub to a polar ice cap and fire off a test missile, proving to the U.S. that the Soviets are indeed capable of launching a nuclear war.

That moment comes a full hour into the film, after Vostrikov, ever the taskmaster, has shaken his ship to its nuclear core with a series of test drills meant to induce excitement, but which instead only spark modest interest – as you’d expect from a series of imaginary fires and leaks.

The film does generate some heat when the ship’s nuclear reactor springs a real leak midway through, but as Vostrikov and Polenin come to throws over how to best deal with the unfolding crisis, which allegedly could have started World War III had the bombs gone off, Bigelow loses her grip, favoring moments that sink into cheesy melodrama and tacking on a forced ending that never offers the emotional punch it seeks.

Grade: C+

On video and DVD

CROSSROADS. Directed by Tamra Davis, written by Shonda Rhimes, 90 minutes, rated PG-13.

Tamra Davis’ “Crossroads” asks audiences to consider the prospect of life without Britney Spears’ virginity – which, not surprisingly, turns out to have as much kick as a can of caffeine-free Diet Pepsi.

In the film, Spears is Lucy, the goody-goody valedictorian of her high school graduating class who was abandoned by her mother, Caroline (Kim Cattrall), at age 3, is considered to be the class nerd, and who is lovingly bullied by her overprotective father (Dan Aykroyd) to become a nurse.

Yes, Lucy is a stretch for Spears, but unlike Mariah Carey’s unforgettable performance in “Glitter,” a modern camp classic and one of the best bad films ever, she is only occasionally humiliated by the role – which, as star vehicles go, isn’t half bad.

Along with her estranged childhood friends, the pregnant Mimi (Taryn Manning) and the pretty Kit (Zoe Saldana), Lucy leaves her small Georgia town for a road trip to Los Angeles, where she falls for Ben (Anson Mount), a tattooed “hottie” who, it’s rumored, once murdered a man in an act of rage and spent time in the big house. Predictably, a whirlwind of melodramas erupts as these four get closer to the bright lights of L.A.

As bad as the material often is, Spears holds the screen better than you might expect. But what’s truly curious is this: At the end of the movie, when she takes to the stage to hiccup her hit single, “I’m Not a Girl, Not Yet a Woman,” the crowd of Britney fans at my screening last February burst into an unexpected fit of giggles.

Were they laughing at her performance? The song’s ambiguous lyrics? Or because they finally realized what Britney Spears is?

Grade: C-

Christopher Smith’s reviews appear Mondays and Fridays in Style, occasionally on E! Entertainment’s “E! News Weekend,” Tuesdays on “NEWS CENTER at 5” and Thursdays on “NEWS CENTER at 5:30” on WLBZ-2 and WCSH-6. He can be reached at BDNFilm1@aol.com.