2-20: Return to Tomorrow

The Enterprise's test of Dr. Daystrom's greatly enhanced computer becomes deadly.

The Exeter is found drifting in space, its crew dead from a mysterious disease, except its missing captain.

Kirk, Uhura, and Chekhov are abducted and forced into combat games with other captives.

The Enterprise is commandeered by members of the Kelvan empire, seeking to return to the Andromeda galaxy.

Several crew members are possessed by advanced non-corporeal beings.