Smallville - Season 7, Episode 1
When Clark Kent confronts Bizarro, the last wraith from the Phantom Zone, the ensuing fight causes the dam to break, unleashing a torrent of water. Having just been arrested for Lana Lang's murder, Lex Luthor is submerged under water in a patrol car until a mysterious young woman saves him. Lois manages to pull Chloe to safety, but Chloe is pronounced dead at the hospital. And the woman who saved Lex reappears at the Kent farm.