"We want to explore what happened to Desmond in prison; how he ended up there, and why they want him back."

Desmond stays on the freighter. And you'll see more shenanigans on the freighter.

    * Ben was caught accidentally by Danielle's trap and we will find out why.
    * We will learn why Ben was travelling across the island and why he ended up in Danielle's trap.
    * Ben and the real Henry Gale "had words".

Ben was lying to Locke when he told him he didn't know anything about the smoke monster.

    *  "You will be getting the detailed version of what exactly happened to Michael in between Ben sending him and Walt off the island and when we first meet him behind the wheel of that car."
    * "Michael becomes really pivotal to the end of the season. His return will have a lot of impact on the other characters."

"Miles isn't here to make friends. He's here for something else. And it ain't what he told us at the end of Episode 2. (Ben.)"

Jin, Sawyer and Locke are alive on the Island in the future.