Luc Besson's Lucy is based on a lie.

The general premise is that a young woman named Lucy (Scarlett Johansson) gets abducted by a gang in Taipei and forced to carry a bag of drugs in her abdomen. But when the bag bursts, the drug gives her access to the 90 percent of her brain that most of us never use, making her superhuman. The idea that we only use 10 percent of our brains, however, is a myth—a fact more than a few recent stories recently have taken pride in pointing out. The writer/director, in turn, would like to remind them it's fiction.

"It's not true," Besson says. "The good thing with movies is that you mix up everything and then in the end it looks real."

There are a few more true tidbits in the film for science buffs, though. Like, for example, the fact that Lucy is named after the skeleton of the Australopithecus afarensis found in 1974 that is our most famous early human ancestor. WIRED got on the phone with Besson to ask him about neuroscience and some of Lucy's other secrets.

Besson Knew the '10 Percent' Figure Was Wrong, But Used It Anyway

Although it gets bandied around a bit, the idea that we only use 10 percent of our brains is a scientific myth. Still, the brain does have billions of neurons processing a lot of data that we're basically in the dark about. "The numbers of communication per second is absolutely phenomenal," Besson says. "And we have no access to this information. So it was very easy to me to say, 'What happens if one day we have access to our information—if our brain suddenly makes that connection, and then we can have access to it? We could change our blood pressure; we could change everything."

Lucy Is Intentionally Out of Order So That the Science Makes Sense

The opening of Lucy shows scenes of cell division and prehistoric wildlife intercut with the eponymous heroine being forced into ferrying drugs. Initially, it seems a little out of place, but more than an hour later Besson ties it all things together. "I wanted to de-structure the storytelling, because I wanted the people to be ready at the end to believe something unbelievable," Besson says. "If I was too straightforward, without cheetahs, without cells, without anything, it would be like a thriller and then the end would be weird. So I needed to prep the audience from the beginning, like 'You have to be ready for everything.'"

Lucy Would've Been Boring with a Male Lead

Going back to his earlier films like 1990's La Femme Nikita to Léon: The Professional (1994), Besson is known for writing badass female characters. Lucy is no different. From the beginning she's not particularly tough or intelligent, but when she's pushed (and drug-enhanced) she uses her brains (and a little brawn) to get back at the gang that abducted her and forced her into smuggling drugs. "I'm not male-oriented, like in the ’80s where you have the big muscle guy and the girl is crying in the back," Besson says. "You know the story of Achilles? For me Achilles without the tendon is of no interest. His weakness makes him interesting. That's what I like about women. It's difficult for a woman to compete with a man because he's usually stronger, so women have to be more clever, more intelligent, more sneaky, more everything. They have to find another way and that is so attractive."

Besson Had to Erase a Lot of Scarlett Johansson's Personality For Lucy

His star was "not joking around" when it came to playing the heroine in Lucy, even though Besson jokes that "she had 500 questions" about the film and the role. That was a good thing; once Lucy reaches a certain level of brain functionality, she loses all her empathy and personality. "There is nothing of Lucy that Scarlett can use," Besson says. "We had to reinvent how to move, how to talk, expressions. [Scarlett] was very concerned and very pragmatic, very much about the work. For this type of film you don't need a star, you need an actress."

Lucy Took 9 Years to Make

Besson first got the idea for Lucy nearly a decade ago, after meeting a woman who he thought was trying to be an actress but was actually a neuroscientist. They spoke for hours and "I was fascinated by this subject." Besson spent the next nine years talking with neuroscientists to learn more and writing the script. "I'm like a sponge, I need to know a lot before I can start to make a feature film" he says. "My first idea was to say, 'OK, I want to do a thriller, I want to do something entertaining, but I want some food in it.' You can't talk about the brain and just be goofy. … But when the script was ready, I really, really loved it. I wanted to do it, there was no way I would give this script to anybody else."

Besson Waited For Everyone to Leave Paris for a Holy Day to Film the Movie's Epic Car Chase

It wouldn't be a Besson movie if there wasn't at least one balls-to-the-wall action sequence. Lucy's takes place in broad daylight, as Lucy leads a wild car chase through the streets of Paris. So how did he send Lucy and friends from the Arc de Triomphe to Place de la Concorde—two of the busiest places in the city—without plowing through huge crowds? He waited until the Feast of the Assumption of Mary, a time in France when everyone leaves the cities—like Fourth of July in the States. "Paris is totally empty for three days, except for some Japanese tourists and Chinese tourists, who wake up at 11 a.m. because they're jetlagged anyway," Besson says. "Usually with car chases you can feel that it's some very specific area or very specific hours of the day or night, and I wanted to a car chase in the very worst place in Paris at noon. That was fun to do."

Besson Didn't Want His Movie to Have Heroes—Or Villains

Most thrillers have a quest for power, Besson explains, and there's usually a bad guy who wants it and a good guy who wants to prevent them. In Lucy, an average woman gets the greatest power imaginable and has no choice but to try and pass on her knowledge (which is virtually infinite by the end). "The first line she has when she knows that she's going to get all the power, she says, 'I don't know what to do with it,'" he says. "Usually they know what they want to do with it. They want to destroy, they want to steal, they want to conquer. But at this level of power, the only thing she can do is pass it on. I think it's such a lesson, because that's exactly what the cell—which is the first image of the film—that's what the cell is doing, just passing on everything she knows to the other one."