The Enterprise-A is transporting a party of diplomats when it picks up a mysterious alien signal emanating from a nearby world. The planet’s dense, impenetrable atmosphere makes it unclear if the beacon is a distress signal, an invitation — or a warning to stay away. Spock, Doctor McCoy, and Chekov are part of a team sent to investigate, but an unexpected catastrophe forces a crash-landing. Now the landing party is stranded on a hostile world, unable to communicate with the Enterprise. While Captain Kirk and Saavik race to locate the lost crew, a badly wounded Spock struggles to keep McCoy and the others alive until they can be rescued, even if that means making an unthinkable sacrifice...