Call it a comedy of shocking gravity. Thelma & Louise begins like an episode of I Love Lucy and ends with the impact of Easy Rider. It's a bumpy path between those points, and director Ridley Scott (Black Rain) and first-time screenwriter Callie Khouri don't cushion the ride. The film switches moods violently, and sometimes it just jerks your chain. But this is movie dynamite, detonated by award-caliber performances from Geena Davis and Susan Sarandon in the title roles.

Davis plays Thelma, a…