Peter Parker had his radioactive spider and the Fantastic Four their gamma rays. For Lucy (Scarlett Johansson), the imperilled heroine of Luc Besson's sleek, punchy action caper, superpower comes courtesy of a packet of prototype narcotics that ruptures in her intestine, allowing her to access an extra 90% of her cerebral capacity. Before long, Lucy is an unblinking angel of vengeance, alive to each revolution of the planet and driving hell for leather down the boulevards of Paris. She's like a blend of Marilyn Monroe and the Terminator, as scripted by Ayn Rand.

All of which proves rollickingly entertaining – up to a point. Besson delivers the thrills with aplomb, while Johansson looks to be relishing a role that stands as a kind of populist cousin to her recent, electrifying performance in Jonathan Glazer's Under the Skin. The problem is that the greater Lucy grows, and the more brain power she colonises, the more the plot risks bursting its bounds and blowing out its levels. What breed of monster has Besson created here? Snickering drug dealers are no match for Lucy. The movie itself can barely contain her. Lucy is hopping across millennia; she has her sights set on the cosmos. At the rate she's going, she should reach the outer edge of the galaxy in about 90 minutes flat.