Exile on Vulcan follows the crew of the USS Enterprise, led by Captain Kirk, as they are punished after disobeying direct orders by saving Spock in the previous film, Star Trek III: The Search for Spock. In that film, Kirk and his crew had stolen the Enterprise to rescue Spock's body and rejoin it with his spirit. As they near Earth in 2286, they are warned away by Starfleet Command due to a mysterious vessel approaching and causing chaos. Thanks to Spock's logic, they realize that the only way to communicate with the vessel is through humpback whales, which are extinct. In a desperate attempt, Kirk and his crew use a captured Klingon Bird-of-Prey to travel back in time to the 1980s to find and bring back humpback whales to the future.