The presence of malevolent forces on the island is made obvious to the survivors when Charlie (Dominic Monaghan) and Claire (Emilie de Raven) are kidnapped. The number one suspect is Ethan Rom (William Mapother), the "interloper" whom Hurley realized had not been a passenger on the plane in the previous episode. Even so, a search party makes a foray into the jungle...where anything can happen and already has! More of Jack's (Matthew Fox) troubled past is revealed through flashbacks, with John Terry making a guest appearance as Jack's father, Dr. Christian Shephard. Elsewhere, Boone (Ian Somerhalder) and Locke (Terry O'Quinn) stumble onto a surprise while they are searching for Charlie and Claire.