Any film theorist worth his or her weight in polysyllabic adjectives knows one of the primary delights of movie-going is branding horror schlock as deep-seated social commentary. A hypothesis concerning “The Ruins”: Society has raised its young to be afraid of vegetables. Not just vegetables, but plants, too, specifically vines of the variety that strangle ominous Mayan ruins and spawn deadly flowers capable of imitating sounds from their surroundings.

If this sounds like a brochure for the land of Scurvy, that’s more or less correct. “The Ruins” continues the trend of horror films featuring attractive American youth running amok in overly exotic third world countries (see 2006’s “Turistas”).

The picture’s a little rosier in the beginning: four American college students on vacation in Mexico having the time of their lives. They carouse drunkenly at the poolside of their all-inclusive, no doubt funded by long Winter Break hours and daddy’s paycheck. They dance in the surf of this foreign land, careening about and dropping expository hints about their lives back home. They make up; they break up.

Enter the mysterious stranger, a German backpacker named Mathias (Joe Anderson). He duly invites the students on his mission to find the archaeological dig where his hypothetical brother has been working, an off-the-beaten-jungle-path Mayan ruin so exclusive it doesn’t have a SixFlags erected alongside it yet. Seeking an adventurous cap to their vacation, the film’s two central couples follow.

Fortunately for “The Ruins,” its cast and crew are of a slightly higher pedigree than its trashy “Apocalypto” concept may suggest. Writer Scott Smith adapted the script from his novel of the same title. This is only the second Hollywood project he’s completed since 1998’s “A Simple Plan.” Considering “A Simple Plan” delivers one of cinema’s most all-time blistering monologues, it’s easy to cut “The Ruins’” first-act some slack, and doing so reveals unexpected pleasures.

The film subverts the basic survivor framework by providing two couples whose potential to outlast the other is roughly equal. This makes early crosscutting between surprisingly intimate lovers’ quarrels especially tense, as if the audience is holding its breath waiting for one pair to mark themselves as more likely to end up cat food. The obvious choice might be the medical student in training, but he’s also dating Amy (Jena Malone), one of the two female leads.

Jena Malone is a beloved veteran of the girl-next-door circuit. Her chemistry with co-star Laura Ramsey (Stacy) is notable for its apparent ease — and for its disgust, when things go sour later on.

Cinematographer Darius Khondji, who recently worked with Wong Kar-wai on “My Blueberry Nights,” wisely allows certain early scenes to unfold in relatively long takes, the characters’ milling about in screen space creating a creepy sense of abandonment. But if ever there was a case to be made against the overuse of close-ups, this is it — the diminishing sense of horror in the last act neatly corresponds with the gradual tightening of focus.

The last minute is dull and cheap, coming off more like a sore loser’s parting shot than an eerie final blow, but that doesn’t necessarily mean horror aficionados won’t have fun. After all, we’ve finally gotten that vegetable thesis out of the way.

“The Ruins” was written by Scott Smith and directed by Cartre Smith. It received two out of three stars.