One thing the great Michael Shannon, the best working actor without an Oscar to his name, almost never gets in his movies is “the girl.”

With a scowl that scares, looks that could have been carved by a hatchet and the nasal, sharp-edged voice to match, his “baggage” gets him cast as hit-men, cops and villains more often than not.

So when we see him, naked and in bed with the equally naked Imogen Poots in the opening moments of “Frank & Lola,” we’re a little alarmed — for her. Frank may profess to be over-the-moon for Lola, but lines such as “I never said I was a gentleman” and “I’m not playing games” have menace, even if they’re just supposed to be pillow talk.

That’s when writer-director Matthew Ross hits us with the first surprise. Sure, she’s in love. Yeah, she’s up for sex. But “Maybe you could hold me down” is a bit of a head-snapper.

Ross lured a very good cast for his brooding tale of brittle love, sexual gamesmanship and the consequences of infidelity when you’re dating a guy you just sense has “a history of violence.”

They’re in Vegas. Frank’s a chef in a “theme” restaurant whose theme could be “Sweeney Todd.” Blood-spattered chef’s jackets are the rule, emphasizing that they cook meat there. He moonlights as a personal chef to the local bourgeois. Lola is fresh out of design school. They’re years apart in age, but even though he seems to be out of his league, they kind of make sense. Lola has…issues.

The minute she’s talked into a job by the rich flirt (Justin Long, out of his depth) in a bar, we sense trouble. So does Frank. And the rich guy’s offer to hook him up with a prestige gig don’t defuse the situation.

“You tell him you’re in love iwht a man who owns an extremely sharp set of knives.”

But the jealous rage that we, Frank and Lola see coming is trickier and deeper than it seems. The motivation veers off formula, and Frank’s response may be pointed in the wrong direction, time and again.

Ross, who once directed a short “Inspired by Brett Easton Ellis,” did what first-time feature writer-directors have to do to get their debut off the ground. He created a wonderful, expectations-defying character that lured Shannon in. Solid supporting players (Long seems miscast, but has a little name recognition) followed.

But the movie unravels as its surprises become melodramatic flourishes, undercutting its tension with coincidences, lapses in motivation and head-scratching responses to situations that are pretty conventional — cut and dried — despite the lurid, Vegas/Ellis undertones.

Shannon is a lot of fun as the sort of chef you don’t want to summon to your table after eating his fabulous meal. His reading of “Nobody knows how to eat any more” is both a complaint, and a threat.

And crossing him, sexually? What pretty young thing would ever think that’s not her queue to flee the country?

“Two hours ago I would’ve crawled through glass for you.” Yeah, he means it. No, you and we don’t know what he’s doing next. But we have our suspicions.

Poots makes Lola interesting, even if she doesn’t suggest the femme fatale — capable of saying anything — that the role requires to maintain the movie’s mystery. Rosanna Arquette plays Lola’s jet set journalist mom, a bit of a boozy floozy. Michael “Girl With the Dragon Tattoo” Nyqvist makes a third act appearance that adds a little chill.

But as in “Nocturnal Animals,” it is Shannon who makes it all worth watching. He’s the guy who lifts a self-conscious “psycho-sexual mystery” out of the mundane and keeps us interested, even as the director distractedly wanders off to play with the lurid lighting and the posh settings when he should have been fretting more over the tension and logic of his script, making it more of a mystery.

Shannon may indeed “get the girl.” We need to be more in the dark, though, about whether she’ll still have a pulse when he does.

MPAA Rating: unrated, with violence, nudity, sexual situations

Cast: Michael Shannon, Imogen Poots, Rosanna Arquette, Michael Nyqvist, Justin Long

Credits:Written and directed by Matthew Ross. An Archlight/Palladin release.

Running time: 1:28