‘Bad Samaritan’ lacks the elegance to make its dark premise entertaining

“Bad Samaritan” is a horrible little movie with two things going for it: one wigged-out performance and one genuinely terrific line, so great you want to be able to say that it saves the film.

It doesn’t. Not even close. But man, is it outstanding.

It’s also a pretty big spoiler, so just know that it exists out there, floating around, a reward you’ll never want to earn, because no matter how enjoyable it is, it’s not worth the trouble of getting there. So that’s really all that can be said about that.

But the performance, that we can talk about.

It arrives courtesy of David Tennant, best known as a former Dr. Who. He plays Cale Erendreich, a trust-fund psychopath with all the money and time he needs to kidnap and torture women without so much as ruffling the part in his hair.

First things first, alas. At the beginning of the film soulful struggling artist Sean Falco (Robert Sheehan) works parking cars as a valet in Portland, Oregon, while moonlighting as a thief. He and his partner Derek Sandoval (Carlito Olivero) have a nice little scam going. When a wealthy person drops off a car to eat at the restaurant where they work, one monitors the progress of dinner while the other, instead of parking the car, uses the GPS to find the driver’s home and loot it of small-but-valuable items, ideally small enough not to be missed but valuable enough to sell.

It’s all working well enough until one day Erendreich roars up in his Maserati. Sean thinks he’s hit the jackpot, until while snooping around he finds a woman (Kerry Condon) bound, gagged and beaten. Naturally Erendreich is finishing dinner, so he has to rush back to the restaurant, but not before promising the woman he’ll rescue her.

Easier said than done, thanks in part to Erendreich’s riches and resources, as well as a spectacularly inept police force, whose inability to do anything is matched only by the local office of the FBI.

Long story short: Erendreich is on to Sean, and delights in destroying his life bit by bit. In a better movie this would play out as a tense series of torturous mind games. In director Dean Devlin’s hands it plays out like trimming your nails with a meat cleaver. Sure, it’s effective, but it’s not very elegant.

Tennant has a blast by chewing every scene he’s in. He’s got a back story explained, sort of, in a repeated bit of nonsense with a horse when he was a child. Now he romps around yelling, “I must correct you” to various victims.

Sheehan tries to make Sean a sensitive sort, and Condon does a nice job of being more than a victim. Beyond that no one really seems like they’re trying (that goes for screenwriter Brandon Boyce, as well).

Then, out of the blue, comes that one bit of dialogue, delivered perfectly, as shocking for its suddenness as its competence. If movies were made up of one line, “Bad Samaritan” would be a good one.

But they aren’t, and it’s not. Not by a long shot.

★1⁄2

Electric Entertainment presents a film directed by Dean Devlin and written by Brandon Boyce. Rated R (for violence, language throughout, some drug use and brief nudity). Running time: 107 minutes. Opens Friday at local theaters.