Spock has hijacked the Enterprise and taken it within range of the forbidden planet of Talos IV. At his court martial, he produces evidence of Capt Pike's first contacts with the Talosians.
As Mr Spock conducts his own defence, the Enterprise receives transmissions from Talos IV detailing Capt Pike's first encounter with the Talosians.
Pursuing an alien vessel which has decimated a Federation outpost, the Enterprise is halted by an unknown force and Captain Kirk finds himself in a nightmarish struggle to save himself and his crew from almost certain death.
The Enterprise is sent on a diplomatic mission to one of the protagonists in a 500-year-old space war, only to discover that the starship is itself destined for destruction.