in ‘Lucy,’ Scarlett Johansson’s Powerful Mind Is Unlocked and Ready to Kill

This image released by Universal Pictures shows Morgan Freeman, left, and Scarlett Johansson in a scene from "Lucy." (AP Photo/Universal Pictures, Jessica Forde)

This image released by Universal Pictures shows Morgan Freeman, left, and Scarlett Johansson in a scene from "Lucy." (AP Photo/Universal Pictures, Jessica Forde)

The theme of Lucy may be the potential of the human mind, but the less time any human spends thinking about its largely nonsensical plot, the better. The slickly executed bullet-riddler about brainpower can be enjoyed only by cutting off all attempts at logic and rational thought.

Director Luc Besson — the French filmmaker who placed female stars at the center of such action movies as La Femme Nikita, The Professional and The Fifth Element — recruits Scarlett Johansson to serve as his one-woman army here. She plays Lucy, an American in Taipei who gets thrust into the role of drug mule during a nail-biting opening sequence that generates a tension the rest of the film never matches. After delivering a silver briefcase to a Tokyo crime boss and begging for her life, Lucy discovers that the case contains a powdered version of the chemical CPH4, a substance that, with its bright blue hues, calls to mind Walter White’s crystal meth in Breaking Bad. Soon after, Lucy and a few other men wind up with bags of CPH4 surgically embedded in their intestines, destined for transport to multiple European countries. But before Lucy arrives at her destination, the substance begins to leak into her bloodstream, activating a rapidly increasing percentage of her brain. This transforms her into an increasingly unstoppable superwoman, for reasons that defy the basic principles of science as well as science fiction.

This is yet another of those movies premised on the “fact” that normal people use only 10 percent of their brain, a supposition that scientists already debunked when the 2011 thriller Limitless constructed its narrative around the same premise. Nevertheless, Besson tries to sell the same bill of goods here. He does it, in part, by relying on the most authoritative cinematic tool currently known to Hollywood: Morgan Freeman.

As Professor Norman, Freeman delivers a lecture to a room of Paris intellectuals in which he explains what men and women could achieve if only they could light up every corner of the cerebellum. Besson cuts between scenes of Freeman discussing that hypothetical and Johansson acting on it, as her mind overloads with memories and information that somehow also turn her into an assassin capable of engaging in hyper-violent versions of Jedi mind tricks.

In those moments, Freeman and Johansson act like a tag team assigned to persuade the audience to believe in the ridiculous; he delivers the verbal, while Johansson — all firing synapses and blazing guns — provides the visual aids. Why, exactly, does the increasing stimulation of underused brain cells turn Johansson into someone who can read other people’s thoughts, control telecommunication devices and turn her hair from blonde to jet-black? Look, I don’t know, but Morgan Freeman thinks it’s possible. The guy who narrates the Science Channel show Through the Wormhole must know what he’s talking about, right?

As Lucy, Johansson hopscotches between vulnerability and a robotic commitment to execute whatever her sophisticated, internal data processor tells her to do. Her performance is just grounded enough to keep Besson’s occasionally inventive, sometimes silly visual flourishes — including an overreliance on random footage seemingly pulled from nature documentaries — from turning the movie into self-parody.

Besson clearly understands that the film’s central myth endures because people are intrigued by the prospect of activating our whole heads. He runs with that idea full-tilt and at top speed, even if it means turning Lucy into a walking X-ray machine/broadcast network/telekinetic demigod. It’s possible to be swept away by the fun in all that, but only if you’re capable of silencing the messages bubbling through your own gray matter and ignoring the inevitable questions. Like this one: If Johansson’s Lucy has such command of her mental faculties that she is, essentially, the most enlightened being on the planet, shouldn’t she be able to figure out how to get what she wants without causing so much destruction and loss of life?

Not in this cinematic world, where the more you know, the more equipped you are to kill.

Lucy is r ated R. Contains strong violence, disturbing images and sexuality. 89 minutes.