The Greek gods made for great storytelling because they had outsized powers and petty grievances. These Gen-Y demigods are no different. In the ’90s, Zeus (Sean Bean) decreed that Olympian parents could have no contact with their half-breed offspring, thus creating a whole generation of kids with daddy issues. Among them is Percy (Logan Lerman), a teen who’s just learned that he’s the son of Poseidon of the sea (Kevin McKidd) and Sally of Manhattan (Catherine Keener). And Uncle Zeus has just accused him of stealing his lightning bolt, triggering a war of the gods set to detonate on the summer solstice. The unwieldy title tips the studio’s hand that they’d like to make a franchise out of Rick Riordan’s popular novels—they’ve even hired director Chris Columbus for some of Harry Potter’s luck—but this first installment isn’t a knockout. Lerman is a handsome kid and a fine dramatic actor, but his Percy is so slim on brains and wonder that we’re just passively along for the ride. As Grover, Percy’s satyr bodyguard, Brandon T. Jackson (Alpa Chino in Tropic Thunder) has that missing spark, even if we groan at watching a goat-legged hipster get busy on the dance floor. And if you’re willing to forgive a flick that gives Athena a daughter (Google it), Alexandra Daddario has a lovely Grecian sternness to her face and she slings a sword like she means it. After the trio meets up at a camp for demigods (which is crowded to the brim—looks like abstinence-only education doesn’t work on Olympus either), they set off to convince Zeus and Hades (Steve Coogan) of Percy’s innocence, an odyssey that sees them confronting Medusa (Uma Thurman) in a twee statuary shoppe and getting sidelined by the pleasures of the Lotus Casino in Vegas (my favorite nudge to the ribs). Oddly, the CGI wizardry on display is bottom of the barrel—if you’re going to half-ass making a hydra, you’d be better off with Ray Harryhausen’s claymation.