The Federation starship Enterprise returns to Earth following a battle with the superhuman Khan Noonien Singh, who tried to destroy the Enterprise by detonating an experimental terraforming device known as Genesis. The casualties of the fight include Admiral James T. Kirk's Vulcan friend, Spock, whose casket was launched into space and eventually landed on the planet created by the Genesis Device. Upon arriving at Earth Spacedock, Doctor Leonard McCoy begins to act strangely and is detained. The commander of Starfleet, Admiral Morrow, visits the Enterprise and informs the crew the ship is to be decommissioned; the crew is instructed not to speak about Genesis due to political fallout over the device.