“Lost” is the first episode of the fifth and final season of Eureka.
At the end of the previous episode, “One Giant Leap…” (this episode doesn’t follow after the Christmas special, “Do You See What I See?”), the Astraeus ship had launched to an unknown destination, by itself and with Allison on board, despite Carter’s attempts to stop it, and Jo had left Eureka.
The crew manages to land the ship safely on what they think is Titan. Only it isn’t – it’s Eureka. Worse, it’s Eureka four years in the future, and there have been changes. Jo isn’t head of Global Dynamics security – Deputy Andy is, and he’s got a whole bunch of Andys working for him. He also doesn’t seem as nice as he used to be. The head of GD itself is S.A.R.A.H. – Carter’s smart house. And those are only some of the changes.
The crew try and cope with a changed, and somewhat worrying, world, stopping Andy in the process, but there’s a hint that not everything may be as it seems.