Luc Besson: Scarlett Johansson is perfect on set

French director Luc Besson has returned to science fiction with a new thriller starring Scarlett Johansson and Morgan Freeman.

Some of Besson's best-known films include Leon, The Fifth Element, The Big Blue and La Femme Nikita.

In Lucy, Scarlett Johansson stars as a young woman caught up in a dangerous drug deal that sees her inadvertently acting as a drug mule, carrying a substance that gives her superhuman abilities.

Besson told Sophie van Brugen why he wanted to make a "fun" thriller with a philosophical theme.