Desmond, Jack, and Evil Locke all went to the light source. Desmond unplugged the light and the island started to sink. A side-effect of the light going out was that Jack and Evil Locke became mortal. After a fight where Jack was stabbed, Kate shot Locke and killed him.
Hurley took Jack's place as the island's protector with Ben as his advisor. Jack died in the bamboo forest where he woke up in episode 1. Kate, Claire, Sawyer, Richard, Lepetis, and Miles escaped on a plane.
It's not pointed out, but Rose and Bernard also were left on the island.
The "side flashes" this season were the "ideal lives" of the Oceanic survivors. They were all dead inside this "reality", just waiting for the moment when they would remember their former lives and pass on to the next stage in the afterlife. Which they did at the end of the episode.
|