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.
The French woman — Rousseau — shocks the survivors by showing up with a dire warning about “the others.” Meanwhile, Michael and Jin ready the raft for sailing.
Jack suspects foul play when Michael becomes violently ill while building the raft. Meanwhile a secret from Kate’s past is revealed, the mysterious hatch is shown to a few of the survivors, and Walt gives Locke a warning.
After burying one of their own, tempers flare as the castaways’ suspicions of each other grow — and an unlikely survivor vows revenge. Meanwhile, Claire and Charlie struggle to calm her newborn.
Claire goes into labor while a helpless Charlie goes into panic mode. Meanwhile Locke is missing, Jack tends to a wounded survivor and Sayid presents Shannon with a romantic surprise.