Jack, Kate, and Sawyer are prisoners of the mysterious "Others." After their captors drug them and take blood samples, they are held in separate areas. The camp leaders--Ben (Henry Gale), Mr. Friendly and a new woman, Juliet--try to make the castaways adjust to their new circumstances.
Flashbacks reveal more about Jack's past with his father and his wife Sarah.
Sun and Jin's lives are put in danger when Sayid tries to locate Jack and the other missing castaways. Sayid also creates a plan in order to get the attention of the "Others" on the beach. Meanwhile, Henry (i.e. Ben) gives Jack an offer that is very tempting in exchange for his cooperation. Lastly, Kate and Sawyer must adjust to harsh conditions that are being forced upon them by "The Others."
Locke, Eko and Desmond are found scattered about the island after the implosion of the hatch. Locke receives a message from the Island asking him to fix the situation he caused.
Hurley returns to the beach camp to report the imprisonment of Kate, Jack and Sawyer by the Others.
Desmond has been fundamentally altered by the implosion, giving him a mysterious new power.
The Others prevent Sawyer and Kate from escaping, leaving Sawyer perplexed by the extent of the measures taken to keep them imprisoned. Jack is asked to use his medical training to save the life of one of the Others. At the beach, Desmond's strange behavior attracts attention. He begins to construct a mysterious device.
A delirious Eko wrestles with past demons; some of the castaways go to the Pearl station to find a computer they can use to locate Jack, Kate and Sawyer; Jack does not know who to trust when two of the Others are at odds with each other.
Jack makes a decision regarding Ben's offer. Sawyer's life is placed in danger when Pickett decides to make good on his threat. Locke discovers a hidden message that may help unlock the island's secrets. Kate recalls memories from the past, which caused her to make an important choice.
Jack has the Others in a desperate situation as he holds Ben's life in his hands. Meanwhile, Kate and Sawyer try to escape from their captors. Flashbacks reveal Juliet's past as a medical researcher in Miami.
After Desmond rescues Claire from drowning, Charlie gets Hurley to help him find out why Desmond has seemed able to predict the future. Desmond recalls exactly what took place in the moments after he turns the key, where he experienced a strange vision of his life prior to his Army days.
As Kate and Sawyer journey back to the main island with Karl, who is exhibiting effects of the brainwashing video, they argue over whether to go back and save Jack. On Hydra island, as Juliet's fate rests in his hands and a power struggle within the Others ensues, Jack recollects the time he spent in Phuket, Thailand and his relationship with Achara, a mysterious tattoo artist.
Kate is still struggling over their decision to leave Jack in the hands of the Others as she and Sawyer return to their camp. Meanwhile, Hurley finds an old van in the jungle and attempts to use it to help a fellow survivor in need of faith and hope. Flashbacks reveal more of Hurley's tumultuous past with the numbers curse.
On their mission to rescue Jack, Kate, Sayid, and Locke stumble upon a mysterious structure surrounded by farm animals and meet its strange inhabitant. Back at the camp, in order to reclaim his belongings, Sawyer plays in a ping-pong competition.
Claire has an idea to send a message to the outside world. Charlie, however, is resistant to the idea, and Desmond tries to sabotage the plan. As Claire tries to get the truth behind their actions out of the pair, she remembers traumatic events from her past. Meanwhile, the rescue party encounters a dangerous obstacle.
When Kate and Locke arrive at the Others' camp, Ben promises to tell Locke the island's secrets as long as he stops his destructive plan, and Kate's reunion with Jack doesn't go very well when she learns that the Others have offered him a deal. More of Locke's troubled past is revealed.
When both Nikki and Paulo apparently die, the rest of the castaways try to figure out what happened to them. In the course of the investigation, the truth about Sun's "kidnapping" comes to light. Flashbacks show what Nikki and Paulo were doing before the crash and why they kept to themselves afterwards.
The Others are vacating their home, and one of the castaways is leaving with them. Kate is knocked out and wakes up in the jungle handcuffed to Juliet. Kate is determined to return to get Jack, while Juliet believes she has been abandoned. The two have to work together in order to survive. Flashbacks show how Kate tried to reconcile with her mother. Meanwhile, Hurley informs Sawyer that a vote will be held on whether or not to banish him. The two concoct a plan to get everyone to like Sawyer so he can stay.
Jack returns, but no one is in the mood for celebrating when they see that Juliet has come back with him. As Juliet struggles to find a way to be accepted, flashbacks show how she came to the island and what she was doing during those three years. She sees a chance to help when Claire suddenly develops a dangerous illness, but Sawyer and Sayid are reluctant to trust her.
Desmond convinces Hurley, Jin, and Charlie to follow him on a trek through the jungle after he receives a series of visions. Flashbacks reveal the time that Desmond spent with a cloister of monks. Meanwhile, a despondent Kate turns to Sawyer for companionship after seeing Jack and Juliet together.
Sun learns what happens to pregnant women on the island. Juliet takes her to the Staff in order to learn the baby's D.O.C. (Date of Conception). Sun recalls how she learned about Jin's parents. Meanwhile, the woman who dropped from the sky is dying, and Desmond and Charlie clash as an adversary arrives who can help her.
After abandoning the Others, Locke takes Sawyer on a trek through the jungle to help him eliminate a common enemy. Meanwhile, back at the beach, the parachutist Naomi has crucial information about flight 815.
Locke confronts Ben and demands that Ben take him to Jacob. Ben complies, but the answers Locke receives are not what he expected. Ben remembers his childhood on the Island, revealing the history of the Dharma Initiative and how the Others came to power. Meanwhile, Juliet's deception is revealed back at the beach, but her and Jack's reactions are quite unexpected.
Charlie makes a list of the best moments of his life. Once again, Desmond has foreseen his death, but this time Charlie decides to face it head on. Jack devises a plan to fight back when the Others arrive, but unexpected developments jeopardize everything. Sayid discovers a way to contact Naomi's ship, but it requires a sacrifice. Everyone is on edge, as the first major confrontation with the Others approaches.
The ambush for the Others goes awry and ends with Sayid, Jin, and Bernard getting captured.
Ben is informed of Charlie's presence in the Looking Glass station and sends Mikhail to "clean up" the situation. He then embarks with Alex to meet the survivors heading for the radio tower.
In spite of increasing concern amongst the survivors, Jack resolutely continues on their trek.
Ben confronts Jack, claiming that Naomi is not who she seems. Meanwhile, Sawyer and Juliet try to come up with a plan to rescue the hostages at the beach.
Inside the Looking Glass, Charlie and Desmond struggle to find a way to shut off the blocking signal.