In the wake of Spock's ultimate deed of sacrifice, Admiral Kirk and the Enterprise crew return to Earth for some essential repairs to their ship. When they arrive at Spacedock, they are shocked to discover that the Enterprise is to be decommissioned. Even worse, Dr. McCoy begins acting strangely and Scotty has been reassigned to another ship. Kirk is forced to steal back the Enterprise and head across space to the Genesis Planet to save Spock and bring him to Vulcan. Unknown to them, the Klingons are planning to steal the secrets of the Genesis Device for their own deadly purpose.