What an untidy mess we have before us in “Gringo.”

Begin with a corporate satire bogged down with weak exposition and weaker characters. Weld that to an action farce with much kill-happy bloodshed and even more boredom as set piece after tedious set piece piles up the stacks of corpses. Pack it with a pretty great cast in essentially pointless roles, and wrap it in a lamebrained script seemingly improvised 10 minutes before the start of filming. Remove any trace of excitement, and, presto: There you have it.

While impressively, classically, spectacularly bad movies can fascinate, no kind of film is worse than one that’s blandly bad. Which “Gringo” is. It’s a blaad movie.

Plot recap for the morbidly curious: David Oyelowo (so fine as Martin Luther King in “Selma”) plays Nigerian immigrant Harold Soyinka, a diligent, meek, caricatured Everyman working in the corporate headquarters of a Chicago pharmaceuticals company. His boss and former college friend Richard Rusk (Joel Edgerton, the brother of the director, Nash Edgerton) is vain, ambitious and corrupt.

Rusk’s second in command, Elaine Markinson (Charlize Theron, an excellent actress when she wants to be) is just as duplicitous and a foul-mouthed jezebel, too. Theron, who fires off enough F-word dialogue to break a swear jar, can’t blame anyone but herself for getting involved in this mess, because she co-produced the film.

The execs travel to Mexico for a shady deal involving a drug cartel, and bring unsuspecting Harold with them as the fall guy. South of the border, amid a narco leader inexplicably obsessed with the Beatles, DEA agents in disguise and an international mercenary at a spiritual crossroads, credulous Harold begins to grasp what awful people he works for and what a dreadful thing they are doing. Oyelowo, fatally miscast as a timid idiot in perpetual mental meltdown, must have felt the same while making the movie.

The worm turns a bit, and the narrative turns even less coherent. All the Mexicans consider the Africa-born Harold a gringo, and a powerful leader, perhaps because he wears a business suit. Counterplots and sidebar stories involving Thandie Newton, Amanda Seyfried and Sharlto Copley add a needless 20 minutes to this death march of entertainment.

The film moves at a chaotic clip, as if hectic editing could make up for its lack of real energy. This is the kind of movie that burns up quickly at the box office but leaves a stench that never really goes away.