Jack suspects foul play when Michael becomes violently ill while building the raft. The suspects include Sawyer and Kate, who compete for the last seat on the raft and do anything possible to prevent each other from getting it. Meanwhile, a secret from Kate's past is revealed to the other survivors on the island.

The French woman-Danielle Rousseau-shocks the survivors by showing up to the camp with a dire warning about "the Others" who are on the island, and the black smoke that precedes them. Meanwhile, Michael and Jin ready the raft for sailing. In flashbacks, we see the survivors final moments before they boarded their fateful flight.

The castaways on the raft are surprised at sea by something unexpected. Meanwhile, remaining islanders attempt to blow open the hatch, and a visitor to the encampment might be a threat to Claire's infant son.

As the truth about Sun's kidnapping by "the Others" comes to her attention, Hurley becomes suspicious of Sawyer's attempt to reveal the mystery behind two fellow survivors, Nikki and Paulo. Through series of flashbacks we will discover what Nikki and Paulo were doing before the crash and how they survived 65 days on the island.

Two outcomes of the detonation of the hydrogen bomb are presented. Flight 815 lands safely at LAX, where Kate escapes from the marshal and Jack learns that his father's body was lost in transit.

When Sawyer escapes from the temple, Kate and Jin are sent to bring him back. Meanwhile, the Others determine Sayid is infected and attempt to poison him. In the flash sideways, Kate, still on the run, takes Claire to a hospital when she goes into labor.

Ilana discovers Ben killed Jacob, so she plans to kill him. Meanwhile, Jack, Hurley and a suicidal Richard visit the Black Rock. In the flash sideways, Ben, a high school teacher, tries to blackmail the school's principal.