Genre: Mystery

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".

While Jack devises a plan to do away with "The Others" once and for all, Sayid uncovers a flaw in "The Others'" system that could lead to everyone's rescue. But it requires Charlie to take on a dangerous task that may make Desmond's premonition come true.

A Charlie-centric episode.

Ben unwillingly divulges information to Locke about the island, taking him on a journey to various locations including strange monuments and the mysterious Jacob. Back at the beach, Juliet's secret is revealed. Flashbacks will show us the origins of DHARMA and the history of the island, including 'the purge.'

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.