We're still digesting all the developments, actions and revelations revealed in this week's Lost episode, "The Substitute."

Read through our detailed analysis and review of the installment now.

But there's not too much time to focus on the past, as Lost's final season continues to move full steam ahead with a new installment next Tuesday. It's titled "Lighthouse" and it will focus on two members of the Shephard family: Claire and Jack.

In the following clip from it, Claire returns and does her best Rousseao impression, right down to a frantic search for a missing child. Check it out:

[video url="http://www.tvfanatic.com/videos/crazy-claire/" title="Crazy Claire"] [/video]

We then flash back sideways to 2004 and see a seemingly different, improved version of Jack. He doesn't look so troubled or drunk in the snippet below, does he?

[video url="http://www.tvfanatic.com/videos/sober-jack/" title="Sober Jack"] [/video]

This fuels our belief that the 2004 world in season six is somehow a series epilogue.

The characters have learned from their pre-crash, on-island mistakes and trials and now have the chance for redemption in a universe that exists as if Oceanic 815 landed safely in Los Angeles. We think that makes sense. At least for now.

All Lost theories are subject to change hourly, however.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.