“Cargo” is a movie that confuses obscurity with mystery. It thinks it is being cryptic in the way it reveals — or, more often, does not reveal — details, when in fact it is being impenetrable and dispassionate. It’s a hard movie to like, and I’m not sure it would be worth the effort anyway.

It’s set aboard The Gull, a cargo ship from North Africa bound for Marseilles, onto which a rootless German youth named Chris (Daniel Bruhl) has stowed away. Once he is discovered, the stern Capt. Brookes (Peter Mullan) puts him to work as a crew member.

But there are strange things afoot on The Gull. One night Chris sees three people being thrown overboard, unable to tell who they are or why they’ve been sentenced to drown in the Mediterranean. Soon after, crew members begin to disappear, leaving only their boots behind. Clearly this is no Love Boat.

Through hushed, stilted conversations with other crewmen, Chris learns that stowaways are common, and that sometimes the way to get rid of them is to throw them overboard, a method that is surely illegal even in international waters. He’s horrified by the news — but it still doesn’t explain what’s happening to the disappearing sailors.

Written by Paul Laverty and directed by documentarian Clive Gordon in his feature-film debut, “Cargo” is a big, serious movie, very grandly shot, scored and edited but utterly obtuse in its presentation. Put simply, we never have any idea what the heck’s going on, and when it’s over, too many questions are left unresolved.

Why does one crewman go crazy and climb to the crow’s nest buck naked? Why are the boots always left behind when men disappear? Who’s actually taking the men away? If it’s who we’re supposed to think it is … come on. That one person against those big, strong men? Please. The film is a frustrating and unsatisfying mystery, a complete waste of the cool old ship it was shot on.

D (1 hr., 30 min.; R, some violence, scattered harsh profanity, some nudity, a bit of sexuality.)