Stripped of everything, the 48 survivors scavenge what they can from the plane for their survival. Some panic. Some pin their hopes on rescue. A few find inner strength they never knew they had-like Kate who, with no medical training, suddenly finds herself suturing the doctor's wounds. The band of friends, family, enemies and strangers must work together against the cruel weather and harsh terrain. But the intense howls of mysterious creatures stalking the jungle fill them all with fear. Fortunately, thanks to the calm leadership of quick-thinking Jack and level-headed Kate, they have hope. But even heroes have secrets, as the survivors will come to learn.

Having escaped the "creature" and retrieved the plane transceiver, a group of the survivors travel to higher ground so they can transmit a signal. En route, they receive a mysterious transmission and encounter another of the island's inhabitants. Meanwhile, back at camp, Jack tends to a wounded man who reveals a secret about Kate.

Jack and Hurley discover an alarming secret about Kate, as the marshal's life hangs in the balance and he suffers a lot of pain. Meanwhile Kate, Charlie, Sawyer, Sayid, Boone and Shannon ponder the mysteries they have begun to uncover and worry that telling the other survivors will cause panic. They decide to lie for the time being. Also, Locke's befriending of Walt disturbs Michael, but Walt is more concerned in finding his dog. Lastly, Kate flashes back to when she was arrested by the marshal in Australia.

The survivors are jolted awake in the middle of the night when wild island beasts (which are wild boars) invade the beach encampment. Kate and Michael join the mysterious Locke on a hunt for food -- and a shocking secret about Locke is revealed. On the hunt for food someone is injured. Meanwhile, some survivors are horrified by Jack's plan for the dead bodies still scattered among the wreckage -- he wants to burn them. Jack sees someone that's not there, and we find out that one of the survivors was not able to walk but now he can.

Jack is nearly delirious from lack of sleep and struggles to overcome the haunting events that brought him to Australia and, subsequently, to the island. Meanwhile, Boone gets caught in a treacherous riptide trying to save a woman who went out swimming. A pregnant Claire's health takes a bad turn from lack of fluids, and a thief may have stolen the last bottles of water. Veronica Hamel guest-stars as Jack's mother, Margo.

Also, Jack flashes back at 12 years old, to find himself on the playground in an altercation with a bully, who ultimately beats him up, and later learns a life lesson from his father.

Walt and the others are shocked when Michael is brutally beaten, but only the non-English-speaking Jin and Sun know the truth behind the attack. Meanwhile Kate, Jack, Sawyer and Sayid argue about where the survivors should camp -- on the beach, where they're more likely to be seen, or in a remote inland valley where fresh water abounds; and Locke discovers Charlie's secret.

Charlie begins a painful journey of withdrawal from drugs, surprisingly aided by Locke, whose true motive for helping Charlie is a mystery. Meanwhile, survivors struggle to find and free Jack when he's buried alive in a cave collapse, and someone might be secretly thwarting Sayid, Kate, and Boone when they enact a plan to find the source of the French transmission.

Sayid's life is placed in grave danger after he stumbles upon the source of the mysterious French transmission, the woman Danielle Rousseau (guest-star Mira Furlan). She was on the distress call and is found alive. Meanwhile, Hurley has a ridiculous plan to make life on the island a little more civilized. The plan involves golf clubs he finds in the debris, and it looks like it just might work. Lastly, we flash back to Sayid's childhood friend Nadia as well as his participation in hostage situations in Iraq.

Claire has a horribly realistic nightmare about her new baby being harmed or kidnapped. Flashbacks reveal Claire's backstory: the former boyfriend who got her pregnant, then abandoned her, and the psychic who convinced her to take the ill-fated flight that landed her on the island. Hurley is shocked and confused when he discovers that Ethan Rom (guest-star William Mapother), another plane crash survivor, does not appear on the flight manifest.

Jack, Kate and Sawyer fight over possession of a newly discovered locked metal briefcase which might contain insights into Kate's mysterious past. Meanwhile, Sayid asks a reluctant Shannon to translate notes he took from the French woman. A rising tide threatens to engulf the fuselage and the entire beach encampment, and Rose and a grieving Charlie tentatively bond over Claire's baffling kidnapping.

After the missing Claire returns with no recollection of what has happened since before she boarded the doomed Oceanic flight 815, Jack and Locke formulate a plan of defense against her kidnapper, the mysterious Ethan (guest-star William Mapother), who threatens to kill off the other survivors one by one unless Claire is returned to him. Meanwhile, the disappointment Charlie feels when Claire does not remember him triggers recollections of a woman he had let down in the past.

Jack tends to a severely wounded Boone after Locke returns him to the caves. In the confusion, Locke slips away to deal with his guilt over the crisis. Meanwhile, Claire unexpectedly goes into labor while deep in the forest.

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.