The reclusive Locke (Terry O'Quinn) is willing to help Charlie (Dominic Monaghan) wean himself away from his drug habit -- but he won't explain why he has suddenly become so generous with his time. Flashbacks reveal how Charlie's life as a rock star and his troubled relationship with his bandmate brother (Neil Hopkins) led to his drug habit in the first place. In other developments, Michael (Harold Perrineau) sets Hurley (Jorge Garcia) straight as to the ethnic origins of Jin (Daniel Dae Kim) and Sun (Yunjin Kim); and the efforts by Sayid (Naveen Andrews), Kate (Evangeline Lilly), and Boone (Ian Somerhalder) to find out who has been sending radio transmissions in French are thwarted by an unknown antagonist. Worse still is the plight of Jack (Matthew Fox), who is buried alive in a collapsing cave. ~ Rovi