Tonight's must-see: “So You Think You Can Dance"

The final six contestants perform.

The fourth and final semifinal round. David Hasselhoff, Brandy and Piers Morgan serve as judges. Regis Philbin hosts.

Rousseau leads Sayid to a mysterious captive in the jungle. Is he one of the Others? Meanwhile, Sawyer discovers that Hurley has done something potentially devastating, and uses the information to blackmail Hurley into helping him track an elusive island creature.

Kid Rock is a suspect in the murder of his limousine driver, who is found dead in the car after being shot through the throat. Across town, Stella is discovered covered in blood in her apartment, where her boyfriend has been shot to death. Stella remembers shooting him, but she isn't clear on all that happened up to that time.