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.

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.

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.

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. Robert Patrick ("Terminator 2: Judgment Day," "The X-File") guest stars.

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.

Jack, Locke and Kate explore the mysterious hatch but Jack decides to wait before going down into the hatch. Kate and Locke aren't so patient. When Shannon chases after Vincent the dog, she encounters a familiar face in the jungle.

Jack, Locke and Kate learn more secrets about the hatch. Meanwhile, after being beaten and taken captive, Sawyer, Michael and Jin wonder if their captors are fellow survivors or the dreaded "Others." Flashbacks reveals more of Locke's past in this episode as well as the introduction of Helen (guest star Katey Segal) who shakes things up even more with her revealing personality and past.

When Charlie's vividly surreal dreams lead him to believe Claire's baby, Aaron, is in danger, Locke suspects Charlie may be using again. Meanwhile, Sawyer encourages Hurley to act on his attraction to Libby.

A mysterious illness that baby Aaron suddenly contracts sends a desperate Claire, Kate and French woman Danielle to return to the same area where Claire was initially kidnapped. It is there where she believes she can find a cure for Aaron's illness. In the meantime, Jack and Locke are doing their best to keep their prisoner a secret from the rest of the survivors on the island.

Libby lends a helping hand to Hurley to support him when he begins to think the island is having a strange effect on him. Hurley begins to see Dave (guest-star Evan Handler, Sex and the City) on the island, who was his friend in the mental institution Hurley was in. Also, Locke's sense of purpose is shaken when the prisoner gives him new information about the hatch.

After discovering something odd just offshore, Jack and Sayid come up with a plan to confront "The Others" and hopefully get Walt back. At the same time there will be an answer to the question of where Michael has been and resolution of him and Walt. Meanwhile, Eko and Locke come to blows as Locke makes a potentially cataclysmic decision regarding the "button" and the hatch. Lastly, Desmond returns and he sheds some more light on his experience on the island in the three years prior to when Locke came down into that hatch.

After discovering something odd just offshore, Jack and Sayid come up with a plan to confront "The Others" and hopefully get Walt back. Meanwhile, Eko and Locke come to blows as Locke makes a potentially cataclysmic decision regarding the "button" and the hatch.

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.

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.

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.

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.

The celebration of Jack's return is cut short when he arrives at the beach with an Other, Juliet, whose flashbacks pick up from where they left off, showing us how she got onto the island and became an other. Meanwhile, Claire is threatened by a strange illness.

The season 3 finale finds the castaways preparing for an invasion by the slightly less mysterious Others, while Charlie and Desmond find more than they were looking for in the underwater "Looking Glass Hatch".

The season 3 finale finds the castaways preparing for an invasion by the slightly less mysterious Others, while Charlie and Desmond find more than they were looking for in the underwater "Looking Glass Hatch".

Lost: Missing Pieces are 13 two- to three-minute stories of compelling, new, never-before-seen moments from the hit television show LOST. These newly-created scenes (not deleted scenes from previous episodes) reveal answers and new details about your favorite characters. For each story, we leave it up to the fans to figure out where these pieces fit into the overall mythology.

Christian is talking with Jack about his wedding, which is later that day. Christian reveals that his father disapproved of him marrying Margo, and that was the reason he didn't wear the watch given to him by his father on his wedding day. However, he tells Jack that he is doing the right thing marrying Sarah and passes the watch to Jack, who immediately puts it on.

Hurley comes out of Rose's and Bernard's tent. Neil comes up, and ask what he is doing. He looks at the bottle of DHARMA Cabernet that Hurley has dropped, and then asks if Hurley is going to make a move on Libby. He asks because he has his eyes upon her himself. Hurley tells him that he just now has a date with Libby. Neil reluctantly relents and walks away.

Ben and Jack play chess. Ben asks Jack if he would consider staying on the Island. Jack asks Ben if he intends to keep his promise to let Jack leave. Ben says that its not all up to him in that the Island will not necessarily let Jack leave. He also tells Jack that if he does leave, there might be a time when he would want to come back.

Michael is tied up, when Juliet walks in. She tells him the boat is his, so that he can take Walt away after he will have saved Ben. She comments that Walt is special, that he's not an ordinary boy, and that's why she is worried about him. Juliet is glad that Michael is going to get Walt away from the Island and assures him that Ben will do what he wants. She then reveals the deal with Ben she has made herself, concerning her sister. Then she mentions Michael's list and wishes him good luck.

Jack is asleep on the beach when Juliet wakes him up. She tells him that since Jack brought her to the camp Sayid and the others have not trusted her and think she is there to hurt them. Before Jack can say he will protect her, Juliet tells him that they are right and she is still working for Ben and she has been sent to the camp to do tests to find out which of the women are pregnant. Jack asks her why she is telling him this and she tells him how she saw Sun's baby the night before and that she is tired of living Ben's dream.

Juliet is outside Room 23 where there is some sort of commotion and an alarm sounding. Ben arrives and Juliet tells him that he (presumably Walt) has done something again and that everybody is too scared to go in there. Juliet suggests that they could bring him back to Michael, but Ben refuses. Ben tells her that Walt is special and that Jacob wanted him there, but Juliet says that he is dangerous. When Ben counters that he is only a child, Juliet brings him outside to show what he has done: a group of dead birds lay on the stairwell.

Dr. Arzt tries to convince Jin and Sun not to move from the beach to the caves as Jack has proposed. When Hurley and Michael tell him they can't understand him, he also expresses his doubts in Jack's role as a leader to them. However he changes his mind and decides to move to the caves after all when the roaring of the monster interrupts their conversation.

Sun is watching Jin fish and then walks into the jungle. There she buries a California drivers license when Michael runs by looking for Vincent. Seeing the license he picks it up and Sun tries to explain that she was going to leave Jin. Michael comforts her telling her it will be okay. The two almost share a kiss but Vincent appears barking before anything can happen, prompting Sun to leave.

Dr. Arzt is catching a spider in the jungle when Michael comes up and asks about the weather conditions for launching the raft. Then Arzt admits he made up the story about the monsoon because he wanted them to get help with the raft as soon as possible. He then tells Michael he went to Sydney to meet a woman whom he had met on the internet, but that she disappeared during their first dinner in a restaurant.

Jack is searching for supplies when he meets Ethan Rom, who gives him a case full of medicine that he says he found in the jungle. Ethan mentions that Claire might have to deliver the baby on the island, and Jack thanks him for his assistance. Ethan tells Jack his own wife died in childbirth along with the baby, and they both hope that rescue is on the way.

Hurley, Michael, and Jin are playing golf on the golf course. After Jin misses a putt to win the game, he goes on a temper-tantrum, shouting in Korean. As Hurley and Michael look on, Jin lets out all of his anger: he is unhappy, he doesn't want to be pitied, nobody understands him, and he is tired of the handcuffs. As Michael and Hurley eventually leave, Jin sits down, half crying, and repeating "I'm so alone."

Juliet is at her home at the Barracks when she notices that the muffins in the oven are burning. After scalding her hand while taking them out, the doorbell rings. It is Amelia. She helps Juliet, getting some ice for her hand, but realizes that something else is troubling Juliet. She asks if it is Ben, and Juliet says that things have gotten awkward between them. Amelia asks if he finally told her how he felt, but Juliet says he didn't; things are complicated. After Amelia further presses Juliet about what is going on, Juliet hints that they are somehow in trouble. Juliet then asks Amelia to keep quiet about something she is about to show her. As Juliet pulls an envelope out of the kitchen drawer, the doorbell rings...

They thought they had met the enemy. They thought they had seen evil. They thought wrong. As the new season begins, the survivors feel that rescue is close at hand, but they don't know whether or not to believe Charlie's final message that the people claiming to liberate them are not who they seem to be. As unlikely alliances are formed, those they thought could be trusted may turn against them, as the enemy of their enemy becomes their friend. But who can be trusted? Is rescue really as close as it seems?

Vincent is running through the jungle on the island, when he encounters Christian Shephard. Christian tells Vincent to find Jack and wake him up because he "has work to do." The first scene of "Pilot, Part 1" then replays with Vincent encountering Jack as he is regaining consciousness.

Locke's hostage may be the key to getting off the island, so Sayid and Kate go in search of their fellow castaway in an attempt to negotiate a peaceful deal.

Sayid and Desmond hit a bit of turbulence on the way to the freighter, which causes Desmond to experience some unexpected side effects.

Jack tries to discover the identity of a body that has washed ashore. Meanwhile, Locke's camp is attacked by Ben's adversaries.

The face-off between the survivors and the freighter people continues, and the Oceanic Six find themselves closer to rescue.

Hurley and Sayid are on the run from the cops after stumbling into trouble at the safehouse; the island survivors come under attack by unknown forces; and an old friend offers some shocking advice to Kate in order to ensure that "the lie" remain a secret.

Locke's mission off the island as Jeremy is revealed.

After meeting old acquaintances Sawyer is forced to continue lying to protect them.

Suspicions about a possible breach intensify after Ben is taken from the infirmary, and a reluctant Miles is forced to work with Hurley when he's asked to deliver an important package to a top Dharma official.

Jack's decision to put a plan in action in order to set things right on the island is met with some strong resistance by those close to him, and Locke assigns Ben a difficult task.

Jack's decision to put a plan in action in order to set things right on the island is met with some strong resistance by those close to him, and Locke assigns Ben a difficult task.

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.

Jack, Sawyer, Kate, Miles and Hurley, struggling to save Sayid, face an ancient secret. Meanwhile, a fake Locke exits the chamber to everyone's awe.

On Jacob's orders, Hurley leads Jack to a lighthouse. Meanwhile, Claire questions an Other she has captured while tending to an injured Jin. In the flash sideways, Jack is a single father trying to bond with his son.

The Man in Black sends Sawyer on a reconnaissance mission to Hydra Island, where he discovers that Charles Widmore has returned to the island with a team of scientists. In the flash sideways, Sawyer is a lonely cop who is still searching for the original Sawyer.

On the island, Widmore subjects Desmond to a large amount of electromagnetic energy as an experiment. In the flash sideways, Desmond, with the aid of Charlie, starts to have visions of his life in the original timeline.

After the remaining survivors are reunited, Sawyer and Jack hatch a plan to divert the Man in Black's attention and leave the island without him on Widmore's submarine, but disastrous consequences await them. In the flash sideways, Jack investigates the cause of Locke's paralysis and offers treatment.

For different reasons, Jack and the Man in Black both use Desmond to extinguish the light at the heart of the island. The island starts disintegrating, but The Man in Black is also made mortal. Still desperate to escape, The Man in Black fights Jack and mortally wounds him, but with help from Kate, Jack kills him. Realizing his destiny, Jack sacrifices himself to relight the heart of the island, so his friends can escape on the Ajira plane. Hurley takes Jack's place as protector of the island and makes Ben the new advisor. The flash sideways is revealed to be a type of limbo, or holding pattern, for the main characters, where they reside until accepting their life and death, and are then able to "let go" and "move on" together.