Supergirl      Director: Craig GillespieCert: 12AStarring: Milly Alcock, Matthias Schoenaerts, Eve Ridley, David Krumholtz, Emily Beecham, David Corenswet, Jason MomoaRunning Time: 1 hr 47 mins“Are you considerably younger than him?” the bereaved Ruthye asks Supergirl of Superman. Her pal notes that the difference is barely a decade. “How come he’s a man and you’re a girl, then?” Ruthye wonders.Not a great deal’s going on in this film’s pretty little head, but it does at least rail back at sexist thinking such as that embodied in the phrase “pretty little head”. Virtually the first image has an alienatingly computer-generated Krypto the Superdog weeing on a picture of Clark Kent’s alter ego. Indeed, Craig Gillespie’s mildly diverting spin-off comes close to pitching its titular Kryptonian refugee as an anti-Superman. She’s not evil (hence just “close”). But she dresses in a crumpled trench coat, drinks like a Pogue and lives in the intergalactic version of a trailer. If this film had been made before 1995 or so, Kara Zor-El, as Supergirl is known to her pals, would have a crushed fag in her mouth at all times. Think of the unshaven layabout that a corrupted Christopher Reeve became in the undervalued Superman III and you’re halfway there.Supergirl is certainly more endurable than James Gunn’s nauseating 2025 take on Superman, but most things that don’t give you pleurisy can reasonably make that claim. A fair bit of the spin-off’s tolerability is down to a spirited performance from the Australian good egg Milly Alcock. Hitherto best known for playing the young Rhaenyra Targaryen in House of the Dragon, she manages the class of boozy swagger that always looks to be containing a potentially fatal vulnerability. But this remains a shamelessly minor work without a single fresh idea in its head.The layabouts in frontier bars look to have been refracted from ancient westerns through the lens of the first Star Wars movie. The “Brigands” who make up the main villain class suggest a version of Mad Max made just west of the Urals. It is bracing to hear the likes of Wet Leg and Wolf Alice on the soundtrack, but the fight choreography merely reworks the shapes of similar rock-scored brawls in films by Guy Ritchie and Matthew Vaughn.The story structure owes something to Gunn’s awful predecessor. As in the Superman film, we are dumped dizzyingly in medias res with scarcely a chance for a preparatory inhale. Kara Zor-El has done her growing up on Earth and is now living in squalor amid beautiful windy landscapes – unmistakably shot in Scotland – when she encounters young Ruthye (the newcomer Eve Ridley), on the run after the brutal murder of her parents by those Brigands. Our cynical heroine is initially reluctant to help her seek revenge, but, when a poison dart sends poor Krypto close to death, her hand is forced. The same hooligans who did for Ruthye’s folks have the only antidote. To the space bus! No, really they do take space buses.Zippy flashbacks to young Kara’s last days on Krypton, featuring David Krumholtz and Emily Beecham as doomed parents, break up the deadeningly familiar space opera with some welcome origin-story action. The infuriating thing about this overpriced movie is that the film-makers come close to solving the problem of Supergirl. Subject of a terrible 1984 film and a decent 2015 TV series, the character has had trouble making distinct sense on screen. Alcock’s swaggering layabout – who doesn’t always close the door when going to the loo – reclaims her as an alien with enjoyably human flaws. The bad news is that, as you have almost certainly guessed, she will be required to pull herself together in what used to be the final reel. Not fair. No fun. Give us back the hungover barfly.In cinemas from Thursday, June 25th