Craig Gillespie’s Supergirl is not a clean film. It is baggy, occasionally rushed, and seems at various points to be actively resisting the idea of arriving anywhere in particular. That it remains compelling throughout is almost entirely down to Milly Alcock, who gives one of the more genuinely impressive performances the superhero genre has produced.

The film adapts Tom King’s Supergirl: Woman of Tomorrow with reasonable fidelity to its spirit if not always its detail. Kara Zor-El joins a young alien girl named Ruthye (Eve Ridley) on a revenge mission across the galaxy, with Matthias Schoenaerts’ Krem of the Yellow Hills as the villain du jour. Jason Momoa arrives mid-film as Lobo, a hardboiled galactic criminal, and immediately makes everything louder, funnier and slightly more dangerous, which is precisely what the film needs at that point.

Gillespie shoots the whole thing with a restlessness that suits the material. There are sequences here that have genuine visual imagination behind them. The flashback to Kara’s dying planet delivers real emotion and insight into the kind of person she has become. The screenplay carries too much cargo, and certain storylines feel like obligations rather than choices.

Schoenaerts is a fine actor stranded in a role that exists purely as a destination; Krem never becomes a villain so much as a raison d’être for both Kara and her young charge. What saves it the film, repeatedly, is the relationship between Kara and Ruthye. Their dynamic gives the film its emotional spine; an unlikely, prickly, gradually earned companionship that grounds the story in something recognisably human.

The comparisons will write themselves, and most of them will be correct. There is something of Mad Max in the film’s propulsive, landscape-driven vengeance logic.  There’s also something of early Guardians of the Galaxy, though Gillespie resists the easy fix of a needle-drop playlist to manufacture feeling. Most tellingly, it has the texture of Joss Whedon’s short-lived cult sci-fi series Firefly, a western transposed to the stars, governed by frontier justice and a moral code assembled on the fly, held together less by institution than by the loyalty of a small and unlikely crew. 

The galaxy Kara travels through is not the gleaming cosmopolitanism of most superhero space opera,;  it is dusty, marginal, and faintly lawless, populated by people who have fallen through the cracks of every empire that has tried to govern them.

David Corenswet’s Superman appears briefly but lands warmly, sketching a cousinly rapport with Alcock that feels both natural and genuinely heartwarming. 

Supergirl is not as assured as Superman, and it knows it too well. What it has instead is temperament; a roughness, a willingness to let its protagonist be wrong, to let scenes breathe past the point of comfort, to trade resolution for texture. Whether that trade-off satisfies will depend entirely on the audience’s tolerance for disorder. For those willing to meet it on its own terms, there is something here worth the effort.