Betrayed by Commander Vaako (Karl Urban, in a brief reprisal), Richard B Riddick (Vin Diesel) finds himself unwillingly exiled on a hostile planet. Injured, and stalked by various indigenous predators, Riddick must overcome a cave full of poisonous scorpion-like creatures in order to hide, re-hydrate and heal. He befriends an infant canine along the way, and over the next few months explores the region until he comes across an abandoned human settlement. Activating an emergency beacon he summons two separate groups of mercenaries — one team lead by Johns (Matthew Nable) and Dahl (Katee Sackhoff), the other by Santana (Jordi Mollà) — just in time for the monsoon, which wakes a dormant population of the previously encountered creatures hungry for the corpses Riddick has typically left in his wake.

Riddick shouldn’t exist. The second sequel to throwaway science fiction thriller from the year 2000, Riddick has overcome the under-performance of its predecessor, 2004’s The Chronicles Of Riddick, to fight another day. With the exception of a small cult following, this has been almost exclusively down to the dogged determination of one man: star Vin Diesel. Not only did the actor finance the film himself while production waited on a crucial bank loan, but he effectively bartered with Universal Pictures for the rights to the character in exchange for a cameo in The Fast And The Furious: Tokyo Drift. I say almost, because director David Twohy has similarly been with the franchise every step of the way, through thick and, well, thicker.

It’s a shame, then, that their efforts haven’t quite paid off. Riddick is not a bad movie exactly, it’s just a movie that could have and — given the time and thought that has clearly gone into it — should have been better. This is not the sort of movie you make for an easy ride, or a quick pay day, and the evidence is on the screen that all involved sweated blood in order to get it made: the creature designs are some of the best in years, the landscapes are impressive if not exactly photo realistic, and Diesel has worked genuine wonders with a character who really shouldn’t be quite so compelling. Indeed, the strongest section comes just after a convoluted and confusing flashback, in which Riddick spends at least half an hour in near silence, immunising himself — and his CGI space dog — against the alien planet’s toxic inhabitants. It shouldn’t work, but it does.

The problems (aside from the convoluted and confusing flashback, which assumes at least A Level study in the previous two movies) begin when Riddick is joined by yet another group of identikit space marines. The most interesting character — basically Riddick from Pitch Black in female form — is wasted within minutes, leaving an asshole, a sex interest and a few dozen walking cadavers to stand in the background while Riddick lurks charismatically in the shadows. Admittedly, prior to the misogyny hitting overdrive, Sackhoff has one or two decent lines, and providing you have a working knowledge of the franchise there are one or two nice references, but for the most part this second act squanders any and all good will on forgettable characters and outdated prejudices.

A triumph of will if little else, Riddick has nevertheless more than earned its place in cinemas. It’s slightly more ambitious than Pitch Black, and not quite as overcrowdedly epic as The Chronicles Of Riddick, but unfortunately an unremarkable finale and jarring displays of sexism and homophobia mar what might have been a mildly pleasant surprise. Still, as Riddick himself admits, he’s come back from worse.