Supergirl

Instead of saving the world, the origin story of Supergirl is more about the titular heroine saving herself.

A coming-of-age superhero saga infused with Gen Z angst, this Superman spinoff generally follows a familiar narrative template, muting the stakes while failing to expand the established mythology in any meaningful way.

As it defines Kara Zor-El less by her own struggles than by the chaos around her, the film unfortunately reinforces her big-screen future as a sidekick rather than a leading lady.

It begins with Kara (Milly Alcock) as a loner and outcast drinking her days away with her rambunctious pooch on a distant planet with a neutral red sun. She mostly ignores check-in calls from her older cousin Superman (David Corenswet), and certainly has little interest in following in those footsteps.

Intermittent flashbacks fill in some details from her childhood, and the harrowing events that led to her arrival on Earth — with its enriching yellow sun — from Krypton years earlier, as well as her eventual retreat to her current outpost.

She’s tracked down by a persistent teenage girl (Eve Ridley) who needs help after a violent family tragedy at the hands of a villainous outlaw (Matthias Schoenarts), who later has the audacity to poison Kara’s dog with the antidote draped around his neck.

Lured out of her self-loathing stupor, Kara’s quest for revenge navigates encounters with various rogues, including a cigar-chomping bounty hunter (Jason Momoa) whose assistance comes with a cost.

Combining charisma and resilience, Australian actress Alcock (“House of the Dragon”) conveys an edgy appeal that outshines the scene-stealing efforts of co-starring humans, canines, and other species.

The disjointed screenplay hints at a more intriguing story of a wayward young woman reluctant to reconcile with her family legacy, discover her powers, and embrace her destiny.

But instead, the film lacks depth during a predictably quirky adventure in which Kara is thrust into an intergalactic conflict, tossing off sardonic one-liners while checking the crowd-pleasing boxes by deploying lasers from her eyes or donning her signature suit — with its fashionable red skirt, golden belt, and thigh-high platform boots.

As directed by Craig Gillespie (Cruella), the result is technically proficient, featuring some innovative creature designs and stylish set pieces as it funnels toward an obligatory effects-driven climactic showdown.

However, in a film that seems more interested in making its protagonist cool rather than compelling, Supergirl rarely takes flight.

Rated PG-13, 108 minutes.