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 the 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 journey to higher ground so they can transmit a signal. On 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. A Kate-centric episode.

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. A Locke-centric episode.

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 (Matthew Fox) 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. A Jack-centric episode.

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. A Jin/Sun-centric episode.

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. A Charlie-centric episode.

Shannon's inhaler runs out and Boone believes Sawyer has the remaining three in his stash. When Sawyer refuses to give them up, Jack and Sayid resort to torturing Sawyer until he agrees to reveal the location of the inhalers. In flashback we hear Sawyer's story and find he is not who he says he is. A Sawyer-centric episode.

Sayid's life is placed in grave danger after he stumbles upon the source of the mysterious French transmission, the woman Danielle Rousseau. 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. A Sayid-centric episode.

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, another plane crash survivor, does not appear on the flight manifest. A Claire-centric episode.

Survivors wonder why Charlie and Claire have been abducted - and by whom - and a search party ventures into the treacherous jungle to look for the pair. Suspicions focus on Ethan Rom, who, it was recently discovered, was not a passenger on the doomed flight. Jack battles inner demons relating to his father, while Boone and Locke discover another island mystery. A Jack-centric episode.

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. A Kate-centric episode.

When Locke learns that Boone wants to share their secret with Shannon, Locke decides to teach him a lesson. This leads to Shannon's life being placed in what seems like peril. Boone and Shannon's dark past is revealed in a shocking backstory that recalls their relationship right before the plane crash and presages the return of the beast. Kate, who has become a confidante to the soft-spoken Sun, is puzzled by Sun's mysterious behavior and the revelation that she can speak English. A hungry Hurley must convince Jin to share his fish by making up for offending Jin by rejecting his offer of raw fish early on, or he'll continue to suffer digestive problems from the limited island diet. A Boone/Shannon-centric episode.

Violence ensues and a mysterious island beast makes a re-appearance when Michael and Locke clash over Walt's upbringing. Meanwhile, Charlie is tempted to read the missing Claire's diary, and Sayid enlists Shannon to help decipher the French woman's map. A Michael/Walt-centric episode.

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, 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. A Charlie-centric episode.

Kate and Sawyer divulge dark secrets to each other while tracking a renegade boar that Sawyer swears is purposely harassing him. Hurley and Sayid worry that Charlie is losing it after facing a brush with death and killing Ethan with 6 bullets to the chest. A shocking prior connection between Sawyer and Jack is revealed in a flashback which shows Sawyer meeting Jack's father in a bar. A Sawyer-centric episode.

When the raft the survivors have been building mysteriously burns down, Michael is convinced that Jin is responsible for the sabotage, which only serves to escalate their rivalry. Meanwhile, Sun stuns her fellow survivors with a surprising revelation, and Boone gives Sayid a warning about his step-sister Shannon. Lastly, more details of Jin and Sun's troubled marriage are revealed through flashbacks. A Jin/Sun-centric episode.

When Hurley becomes obsessed with the French woman and heads into the jungle to find her, Jack, Sayid and Charlie have no choice but to follow. Meanwhile, Locke asks Claire to help build a mysterious item, which is later revealed to be a cradle for Claire's baby. Hurley flashes back to the hugely life-altering experience he had before boarding the plane. He wins the lottery - the number-one thing Americans dream about - but it ends up being the worst thing that could have happened to him. The winning numbers, and their source, were apparently cursed and have brought harm to everyone Hurley loves. We learn some of the spooky story behind the numbers and their connection to the island. A Hurley-centric episode.

Locke thinks he's being sent a sign on how to get the hatch open, and he and Boone venture inland. Locke begins to have difficulties with walking as he and Boone try to find a way into the hatch. Jack is reluctant to offer assistance when Sawyer begins to experience excruciating headaches and needs glasses. In this episode we learn more about Locke's shocking and tragic encounter with his scheming biological parents. Lastly, as Locke confronts his troubled past and struggles to open the hatch, Boone is seriously injured after an accident involving a plane that the pair found in the forest. A Locke-centric episode.

Jack tends to a severely wounded Boone after Locke returns him to the caves. Sun gives Jack some much-needed medical assistance and Sayid presents Shannon with a grand romantic surprise when they're alone. Claire unexpectedly goes into labor in the forest, Jack is unable to deliver the baby, and Kate, Charlie and Jin go into panic mode when they must tend to Claire themselves. Having returned Boone to Jack, Locke disappears back into the forest amid the chaos. A Jack-centric episode.

Jack goes after Locke for lying about Boone's accident whilst Shannon enlists the help of Sayid to avenge her brother's alleged murder. In Sayid's flashback, the CIA convince him to help them catch a suicide bomber. A Sayid-centric episode.

Jack suspects foul play when Michael becomes violently ill while building the raft. 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 -- she is a runaway fugitive. The mysterious hatch is shown to Jack, who sides with Locke over Sayid in favor of opening it. Walt warns Locke not to open the hatch. Walt also admits to his father Michael that he burned the raft the first time, and changes his mind about leaving the island once he realizes Locke's plan for the hatch. Lastly, flashbacks of Kate's past reveal happier times with the love of her life, Tom, prior to his death and a visit to her ill mother. A Kate-centric episode.

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. Danielle takes Jack, Locke, Kate, Hurley, and Arzt on a trek to the Black Rock. However, once they reach the Dark Territory, Arzt (who had previously gone back to camp) comes running with the real Beast hot on his heels. Fortunately, Locke's calm demeanor seems to ease the security system, as Danielle calls it, and it heads in the other direction. They eventually reach the Black Rock, which turns out to be a wooden ship. Black smoke is an ominous sign as the raft sets sail after an accidental delay. Jin and Sun make up, and Walt decides to give the dog Vincent to Shannon since there is no room on the boat. Black smoke continues to rise.

The castaways who make it onto the raft are surprised at sea by something that unexpectedly happens -- they make their first contact with others out at sea, but meet disastrous results. Meanwhile, remaining islanders attempt to blow open the hatch that's in the forest, but this proves to be more difficult than expected. Another survivor on the island dies. Visiting French woman Danielle Rousseau becomes a threat to Claire's infant son as she decides to kidnap him and bring him into the woods for the others to have in order to save the rest. Lastly, flashbacks show us all the survivors in the moments before the doomed flight took off.