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 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.

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

Juliet receives an unwelcome visit from someone from her past and is given orders to track down Charlotte and Faraday in order to stop them from completing their mission -- by any means necessary. Meanwhile, Ben offers Locke an enticing deal.

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

Sayid goes back to the island to bring the rest of the people to the freighter. Ben, Locke, and Hurley go to another Dharma station in order to "move the island".

The remaining island survivors start to feel the effects of the aftermath of moving the island, and Jack and Ben begin their quest to reunite the Oceanic 6 in order to return to the island with Locke's body in an attempt to save their former fellow castaways.

Desmond looks for a woman who might be the key to helping Faraday stop the island's unpredictable movements through time; Locke finds out who has been attacking the survivors.

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

To atone for sins of the past, Ben must attempt to summon the smoke monster in order to be judged.

On the 100th episode milestone for the series, the time of reckoning has begun when Daniel Faraday comes clean regarding what he knows about the island.

Ilana discovers Ben killed Jacob, so she plans to kill him. Meanwhile, Jack, Hurley and a suicidal Richard visit the Black Rock. In the flash sideways, Ben, a high school teacher, tries to blackmail the school's principal.

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.

After Jin is kidnapped and taken to Hydra Island by Widmore's team, the Man in Black confronts Widmore. On the main island, Sun loses her ability to speak English. In the flash sideways, Sun and Jin are abducted after failing to complete a transaction for Sun's father.

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.