 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 . On arriving at Earth Spacedock , Doctor Leonard McCoy begins to act strangely and is detained . Starfleet Admiral Morrow visits the Enterprise and informs the crew the ship is to be decommissioned ; the crew is ordered not to speak about Genesis due to political fallout over the device . 
