Kevin Macdonald's "Black Sea" is overloaded with narrative cargo. We have a sunken treasure (Nazi gold, the best kind), a cramped submarine in search of it (lots of squinty tension and infernal lighting) and an ornery crew (half Brits, half Russians, all at one another's throat). But there's also a tearful love story — sketched in gauzy flashbacks — and there's some awkwardly overlaid working-class economic resentments, which might have been airlifted in from another kind of picture. These elements don't mesh so smoothly as you might hope, but the movie does offer some familiar claustrophobic pleasures, along with unexpected echoes of such films as "The Treasure of the Sierra Madre" and even "Aliens." (There's a scheming corporate weasel on board.) The movie's often fun, but mostly just kinda.

Jude Law is convincingly crusty as a submarine pilot, named Robinson, who has spent most of his life working in marine salvage. When the company by which he's employed abruptly lays him off, he curses the fat cats who run the world and have ruined the economy and pines for his ex-wife, who left him to marry — what else? — some rich guy. Huddling in a pub with other jobless seamen, Robinson hears tell of a Nazi submarine that went down in the Black Sea back in the 1940s, bearing a payload of reichsmarks now worth many millions of dollars. A wealthy American agrees to finance an expedition to retrieve this treasure from under the Russian fleet patrolling above it; in return, this mysterious moneyman wants a big slice of the action and insists on sending along his landlubber assistant, Daniels (Scoot McNairy). Robinson and his Russian pal Blackie (Konstantin Khabensky) assemble a crew, refurbish a rust-bucket sub and are soon underway.

Macdonald, who also directed "The Last King of Scotland" and the newshound thriller "State of Play," effectively cranks up suspense as the crew members, divided by linguistic comprehension, start butting heads and the usual mechanical disasters proliferate. He also renders the digital depths through which the submarine passes with evocative eeriness and, in one long underwater sequence, delivers some top-drawer thrills.

Unfortunately, though Ben Mendelsohn is a memorable wacko, there are too many other shipmates on board to command full individual attention (and the most appealing of them disappears early on). The occasional spasms of violence are also problematic, motivated by nothing more than screenwriter Dennis Kelly's insistence that they transpire. And we can't help wondering, throughout, exactly how Robinson would expect to shift a large pile of gold bars off his ship without anyone's casting covetous eyes upon them.

This is nitpicking, of course. No one expects a genre movie to completely add up. But "Black Sea" would have benefited from a tighter script. Even the twisty ending doesn't really pull the movie together.

Kurt Loder is the film critic for Reason Online. To find out more about Kurt Loder and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.