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.

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 shoulders the burden of ending the island's increasingly violent movements through time; Ben is stymied in his efforts to reunite the Oceanic 6 and bring them back to the island.

The members of Oceanic 6 discover how to get back to the island, but not all of them want to return.

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.

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.