A transporter malfunction splits Captain Kirk into two halves: one meek and indecisive, the other violent and ill tempered. The remaining crew members stranded on the planet cannot be beamed up to the ship until a problem is fixed.
The past three months has left the crew of the Enterprise exhausted and in desperate need of a break, but does this explain McCoy's encounter with a human-sized white rabbit or Kirk crossing paths with the prankster who plagued his days at Starfleet Academy?
The Galileo, under Spock's command, crash-lands on a hostile planet. As the Enterprise races against time to find the shuttlecraft, Spock's strictly logical leadership clashes with the fear and resentment of his crew.