You’d be forgiven if you walked out of Side Effects after its first hour. Director Steven Soderbergh’s (Magic Mike) latest theatrical release starts out as a deliberate, low-burn psychodrama.

Emily Taylor (Rooney Mara, The Girl with the Dragon Tattoo) begins taking antidepressants and seeing psychiatrist Dr. Jonathan Banks (Jude Law, Anna Karenina) after her husband (Channing Tatum, Magic Mike) leaves jail. Emily’s depression is, for a while, seemingly treated until an unexpected catastrophe throws her's and her husband’s lives into ruin, sullying Jonathan’s name in the process.

Up until that catastrophe, Side Effects plays it very low key. While we come to mostly understand Mara and Law’s characters, there’s something persistently aloof and distant about the couple. Unfortunately, this emotional distance makes it difficult to invest in Mara’s plight. And so, the first hour of the film moves a bit too slowly, without sufficient context to be much more than a passable portrait of depression and modern medicine.

But suddenly, after that aforementioned plot twist, the narrative kicks into overdrive. A series of cascading surprises, revelations and breakdowns not only moves the film significantly away from what the trailers and marketing material suggest, but also pulls complete reversals on most of the leading characters.

What emerges from the mess is a film that becomes increasingly at odds with itself — the movie form of an existential crisis.

Side Effects is certainly not a condemnation of big pharmaceuticals or doctors; if anything, the movie ends up criticizing our reaction to medicinal controversies. It also ends up not being much of a character study, eschewing the delicately wrought observations of the first half for a vague revenge thriller.

The final product winds up unsatisfying mostly because Side Effects spends so much time subverting and then counter-subverting expectations. The film bears evidence of considerable, shrewd craft — the aloofness in the first half of the movie turns out to be very intentional — but the way Soderbergh and writer Scott Z. Burns (Contagion) present the series of toppling dominoes exhausts more than it enthralls.

To the movie’s credit, however, the second half is nothing less than captivating. Even when you’re not quite sure if you understand what’s going on, the movie makes you feel that something important is happening and gently nudges you toward the right path.

Soderbergh, acting as his own cinematographer and editor, constructs images with grace and finesse, subtly suggesting various mental states while keeping the second half of the movie moving at a rapid clip.

The cast also manages impressive performances. Mara, in particular, is incredibly frightening in the lead role, while Law strikes a crucial balance between outright emotional exhaustion and sociopathic creepiness.

That tension between Law’s weariness and his insatiable need to clear his name is what powers the last third of the movie. Though Side Effects ends on more of a whimper than a bang, the journey there is at least compelling and interesting enough to warrant the price of admission.