Spock fakes a message from the Enterprise's former commander, Christopher Pike, steals the vessel, and sets it on a locked course for the forbidden planet Talos IV.

The USS Enterprise arrives at Starbase 11 after a subspace message asks it to divert there. When Captain Kirk, Spock, and Dr. Leonard McCoy beam down, they are puzzled when the base commander, Commodore Mendez, tells Kirk the base sent no such message.

Kirk insists that Spock received the urgent request from the former commander of the Enterprise, Fleet Captain Pike. Mendez is surprised that Kirk does not know the news about Captain Pike and leads them to the medical section, explaining that, during an inspection tour of a cadet vessel, one of the baffle plates ruptured. Pike removed the cadets who were still alive, severely exposing himself to delta rays.

Now, confined to a wheelchair, Pike is disfigured and cannot speak, though his mind is unimpaired. His sole means of communication is a flashing light with an accompanying beep: once for yes, twice for no. Spock requests a moment alone with his former commander, and says cryptically to him, "You know why I have come.... I know it is treachery and it is mutiny, but I must do this." Pike can do nothing but repeatedly beep "No."