In addition to being his supposedly last theatrical film director Steven Soderbergh, for a while, would have you believe “Side Effects” could be his best—a complex thriller about psychiatric drugs—only to lose its focus almost entirely and make you wish screenwriter Scott Z. Burns took a shot of Ritalin.

Martin and Emily (Channing Tatum and Rooney Mara) are a New York couple with issues. He has just been released from prison for insider trading, she’s dealing with crippling depression. Enter Dr. Jonathan Banks (played by Jude Law), a psychiatrist being paid handsomely by a pharmaceutical company to conduct new drug trials. Mara’s Emily winds up being a perfect candidate for it but likely didn’t expect to wake up at night sleep-walking, or sleep-other things, either.

Soderbergh and Burns’s (who last worked together on 2011’s “Contagion”) treatment of Americans’ drug culture is compelling. Adverts showing smiling, happy customers and the promise of a “boost” to anyone who needs it is offset by a far more disorienting reality.

Soderbergh coaxes the best performance I’ve seen yet from “Girl with the Dragon Tatoo” star Rooney, who captures accurately how dazed and contrarian the world can be in her pained gaze.They also ask the role of the doctor in all this: drug pusher or patient treater? Friendly ear or propagandist? I’m not giving anything away mentioning that things go very wrong and Banks then becomes a desperate man trying to clear his name and save his career—here is where the film becomes a different movie, a more conventional, far-fetched murder-mystery where devious people are behind an overly intricate plot to attain the usual reasons.

It’s a bit disappointing, but doesn’t detract too much from a very smart film, shot with the disturbing ugliness of a nightmare. It’s hard to shake its chilling “effects”.