Star Trek III: In the wake of Spock's ultimate act of sacrifice, the crew of the U.S.S. Enterprise returns to Earth from the newly formed Genesis planet. Upon arrival, the crew learns that life back home will not be easier. Scotty gets reassigned, Dr. "Bones" McCoy appears to be going insane, and the Enterprise is to be decommissioned. It is only when Kirk is confronted by Spock's father that he learns his old friend may have another chance at life if the crew can survive the Klingon interference and return to the Genesis planet.
Star Trek IV: Branded as fugitives by the very Federation they swore to protect, the crew of the U.S.S. Enterprise dutifully returns to Earth to face charges for crimes committed in the course of rescuing a resurrected Spock. But en route, it is learned that the Earth is being revaged by a strange alien probe demanding a response from a life form that no longer exists. Commandeering a captured Klingon Bird of Prey, Kirk and his crew bend time and space to save Earth and rediscover the meaning of friendship.