Steven Soderbergh claims to be done—at least for the foreseeable future. At age 50, the prolific, protean director is tired of film, taking a hiatus to focus on painting. This choice is but one of many surprise turns in Soderbergh’s career; since he broke through with 1989’s “Sex, Lies and Videotape,” his eclectic catalog has ranged from the bleak “Contagion” and “Che” to the groovy “Magic Mike” and “Ocean’s Eleven.” His new—and potentially final—release, “Side Effects,” falls in the former camp, and while it is no monumental last hurrah, the film is a riveting mélange of some of the strongest Soderbergh staples: stylish direction, a star-studded, committed cast, and a thought-provoking story with more twists than the director’s own career.

Emily (Rooney Mara) is a young, independent New Yorker whose husband Martin (Channing Tatum) has just finished a prison sentence. It soon becomes clear, though, that their relationship lacks its former spark, and that Emily in particular feels this absence.

Mara drains her eyes of life as she did in “The Girl with the Dragon Tattoo;” however, in portraying Emily, Mara has removed Lisbeth’s fiery spunk. Her Emily seems almost dead, yet alive enough to still suffer, and Emily’s melancholia is magnified by the contrast against Tatum’s Martin. Tatum is all swagger here, and the shallowness of his character is intentional; Soderbergh avoids his debonair, heartbreaking smile like the plague. The director casts Martin in shadow and takes every opportunity to zero the camera in on the ghostly, broken Emily.

Enter Dr. Jonathan Banks (Jude Law), who is as put-together as Emily is in shambles. After surviving a not-so-accidental car crash, Emily begins therapy sessions with Dr. Banks, who, as the modern therapist is wont to do, prescribes her pills, first basic varieties and then, after fervent pleading from Emily, a new, experimental drug called “Ablixa.” For just a second, color returns to Emily’s face; Mara expertly injects bits of warmth into the character as she briefly comes back to the land of the living.

Of course, the titular effects have to kick in sometime, and they do so within the first hour of the film: Emily vomits at work, things become fuzzy, and Martin awakes to a sleepwalking Emily blasting rock music and pouring glasses of milk. Ultimately, tragedy strikes. Banks is forced into the spotlight as his credibility as a psychiatrist is challenged, and he starts to grow paranoid and suspect conspiracy. Law, who for the first third of the movie sticks to his usual British charm, is convincingly shaken as his character’s stressors—and beard—grow and his solid exterior starts to dissolve.

The film could have been a simple—albeit gripping—chart of Emily’s fall and the subsequent descent of Banks. But this is a Soderbergh film, in which things cannot simply be how they appear. Just as Soderbergh peppers the movie with upside-down establishing shots, so does “Side Effects” flip its own established order on its head, partially thanks to the enigmatic Dr. Victoria Siebert (Catherine Zeta-Jones, here a dynamo of seductive energy barely contained by thick-rimmed glasses and done-up hair). The final revelation, though completely unexpected, might strike some as cliché or absurd, but it effectively sets up an ending in which not even the most heroic character is left with clean hands.

“Side Effects” constantly engages, even in its long stretches of pure dialogue—Scott Z. Burns’s script moves remarkably fast for its abundant exposition—as well as lengthy periods of silence. The film lightly comments on Americans’ medication dependency; one of the film’s few moments of humor features a patient signing without reading the contract for an experimental treatment, lured by the promise of free pills. A more prominent success, though, is the way it taps into the fear of that dependency, ultimately using this fear to build up audience assumptions before yanking them all away. “Side Effects” may be more about thrill than social critique, but it feels timely and relevant nonetheless.

While the film doesn’t necessarily rise above the rest of his work, Soderbergh is still ending this phase of his career on a high note. Indeed, there wasn’t really a way this film could have felt like an epic finale; it lacks the deep, colorful casts and grandeur of some of his previous work. Soderbergh’s tightly crafted last film, though, still manages to pack his strengths into an effective little thriller, a small creation with powerful effects.

—Staff writer Tree A. Palmedo can be reached at treepalmedo@college.harvard.edu.