In the 26th century the Earth’s International Space Station has expanded to a planet-sized city in deep space, populated by a myriad of alien species and cultures. Major Valerian (Dane Dehaan) and his sidekick Sergeant Laureline (Carla Delevigne), part of a peace-keeping police force, follow a case about a mysterious toxic zone in the centre of the city’s structure that leads to an interplanetary conspiracy and a race to save an entire species.

Valerian and the City of a Thousand Planets gets off to a tremendous start with a striking and hugely emotive opening prologue, depicting humanity’s development and first contact with alien civilizations. The pacing is perfect, as is the choice of music, and it showcases a tremendous sense of production design. From about the five-minute mark the film goes rapidly downhill and never recovers. It is overly long, tediously written and weakly performed. The quality production design is retained throughout, mind, so if you are in the market for an enormously pretty film with almost no other redeeming features then Valerian is the film for you.

The film is a passion project for French filmmaker Luc Besson, whose early career is littered with a lot more good films than anything in recent years. Valerian is simply another step in that slide: you can see the talent who directed the likes of Subway, La Femme Nikita and Leon around the edges and the details, but the strong purity and simplicity of his early works are now bogged down by too many ideas and a sort of late middle-aged flabbiness.

Valerian is based on a popular series of French comic books (bandes desinees) by Pierre Christin and Jean-Claude Mézières, which I have not read – and therefore cannot compare to Besson’s adaptation. On its own merits, the film is a mish-mash of tone and content that seems more interested in throwing things against the wall than in constructing anything streamlined or well-focused. It is, unsurprisingly, often reminiscent of Besson’s 1997 science fiction adventure The Fifth Element, however it lacks that films more relaxed sense of absurdity and the strong lead performances of Bruce Willis and Milla Jovovich.

In their place are Dane Dehaan and Carla Delevigne. Dehaan’s attempt at suave and romantic misfires spectacularly, rendering his character actively unlikeable for much of the film. Delevigne is simply charmless and dull. She has never been a particularly convincing actor, and generally comes across as what she effectively is: a rich heiress and fashion model playing at being a movie star. Neither convinces for a second. Of course it would be unfair to place blame for poor acting solely at Dehaan and Delevigne’s feet: even otherwise talented and experienced actors like Ethan Hawke and Clive Owen perform poorly here. Other notable performances in the film – including pop star Rihanna and jazz legend Herbie Hancock – feel like weird stunts.

Valerian does look really great, with some top-notch design work and generally strong computer-generated effects. The story is nonsense. The performances don’t work. Ultimately it is more than a little boring, and that really is the kiss of death for this kind of film. I am not sure where Luc Besson’s gifts for filmmaking have gone – all I can say is that he clearly has not yet rediscovered them.