The Murder Pact

After witnessing the accidental death of their classmate Heidi, a group of friends - four rich socialites - flee the scene, not realizing that Heidi's roommate Lisa witnessed everything. When Lisa starts to drop hints that she knows about the "accident," the friends decide they can't trust her to stay quiet, and plot to kill Lisa before she rats them out, burying her body beneath the floorboards in one of their basements. Before long, though, the guilt and paranoia starts to consume them, and they become convinced that Lisa may actually be alive and looking for revenge. Based on Edgar Allan Poe's "The Tell-Tale Heart"