The fourth season of this glamorous and increasingly outrageous Aaron Spelling drama kicks off with a bang -- quite literally -- when Kimberly (Marcia Cross) sets off a chain of bombs and blows the apartment complex to smithereens. Despite a heroic rescue by Billy (Andrew Shue), Allison (Courtney Thorne-Smith) is temporarily blinded, and Kimberly nearly drowns after the blast knocks her into the Melrose Place pool.