Slick street-smart attorney Mick Haller (Matthew McConaughey) surveys the courtroom in “The Lincoln Lawyer.”

For a legal drama starring a man best known for running around shirtless on the beaches of Malibu, “The Lincoln Lawyer” is surprisingly engaging and suspenseful. Matthew McConaughey has woken up from his B-movie coma and proven that he can act in a serious dramatic role.

The film, directed by Brad Furman and based on the book of the same name by famed crime novelist Michael Connelly, stars McConaughey as Mick Haller, a street-smart criminal defense lawyer who works out of his Lincoln Town Car in Los Angeles. While casting McConaughey as a stiff corporate attorney from New York would never have worked, he makes for a superb smooth-talking lawyer with a southern drawl, as charismatic and comfortable on the streets as he is in the courtroom.

At the beginning of the film, Haller learns that Louis Roulet (Ryan Philippe), an arrogant but desperate young real estate mogul accused of murdering a prostitute, is willing to pay him a large sum of money to defend him in court. Haller accepts, and his own life thus becomes dangerously tied to Roulet’s intricate crime family, which includes his scheming and controlling mother, Mary Windsor (Frances Fisher). Roulet himself appears manipulative but innocent; Haller, however, soon unearths his true motives, motives that force him to confront his own personal ethics and history.

For a movie with so many intertwined plots and flashbacks, the acting is fairly straightforward and, for the most part, authentic. Ryan Philippe is not particularly likeable as a Beverly Hills ‘bro,’ but most self-entitled, apathetic young men from 90210 are not. His character is believably poised between lackadaisical and frantic—he can’t go to jail, just can’t, not when there are Maseratis to drive and women to woo at bars. Marisa Tomei, as Haller’s ex-wife, plays a hard-edged career woman with little artistic creativity, but it is a character so hackneyed that none is expected—and her surprising candor and chemistry with McConaughey is refreshing.

It is McConaughey whose latent, unexpected ability to act—or maybe just choose a film with a good plot—carries “The Lincoln Lawyer” to surprisingly thrilling heights. He is best when allowed to stretch his comedic wings instead of brooding over legal documents. Whether popping a bottle of Ibuprofen to cure a hangover or outsmarting his client in the courtroom, McConaughey’s bad-boy affectation is pitch-perfect. His character brings to mind Josh Holloway on “Lost,” whose portrayal of James “Sawyer” Ford, another slick Southerner with a penchant for ladies and drinks, was coupled with surprising intellectualism and wit.

For all his efforts, McConaughey can’t always overcome John Romano’s somewhat uninspired script, whose dialogue can’t quite keep pace with its plot. Forced to make earnest emotional statements like “I’ve got to make it right!” and “You know what I’m afraid of now? Evil. Pure evil,” a few of his lines can seem stilted and unnatural. Some heavy-handed courtroom testimony, especially from Mary Windsor, hurts the script with its unintentional hilarity. That said, for the most part, the film’s exchanges—especially Haller’s legal machinations and interactions with his ex-wife—are believable and well-written.

The cinematography fluctuates between the pseudo-artistic and the sweepingly grand. On the one hand, director of photography Lukas Ettlin is overly fond of close-ups and use of the hand-held camera. Both techniques make sense in certain scenes, as when Haller wakes up hung-over or goes on an emotional visit to see an incarcerated former client. There, the immediacy of the camera forces the viewer to relate to his troubled perspective. At other times, though, these gratuitous techniques are disconcerting and erratic—why the viewer needs to feel dizzy while walking through office cubicles, for example, remains a mystery.

Where the cinematography works is at its bombastic best. With its sprawling overhead shots of Los Angeles’s maze of highways, gritty scenes of street life, and pulsing bars and clubs, “The Lincoln Layer” successfully evokes a sense of urgency in the city’s dry heat. Majestic confrontations between Haller and Roulet are set against the city skyline, giving their battle of wills a larger-than-life feeling, while the impressive view from Haller’s bedroom of the city nightscape makes his own decisions resonate beyond the scope of his personal battle.

The film’s inexhaustible supply of plot twists and unexpected outbursts of violence is jarring but admirable in its efforts to confound the viewer. It would be easy to mock Roulet’s last name, a seemingly obvious allusion to the deadly Russian game. Yet unpredictability defines every aspect of “The Lincoln Lawyer,” from Haller’s unconventional relationship with his ex-wife to horrifying revelations about clients he has promised to defend at any cost.

And, what is most surprising, in nearly every scene, McConaughey is wearing a shirt. Did the famous fitness aficionado tone down his workout regimen while filming? Or has he actually decided to start relying on his talent rather than good looks to get by? Whatever the truth, his performance is superb. And that may be the film’s most astonishing twist of all.