Milly Alcock proves she was the right choice for Kara Zor-El, delivering one of the most emotionally believable Kryptonians ever put on screen. Unfortunately, Supergirl struggles beneath an uneven screenplay and a tone that often feels more interested in sounding like James Gunn than trusting Craig Gillespie’s own voice. The result is a frustrating DCU film with real promise that never fully reaches orbit.