In the twenty-third century, Commander Spock, Captain Kirk, and the U.S.S. Enterprise are summoned to Vulcan when its people consider seceding from the Federation and returning to their isolationist ways. Vulcan's savage history becomes fully revealed as Spock, his father Sarek, and Kirk work to preserve the planet's future from anti-Terran factions with hidden agendas. The crisis is twofold for the half-human Spock -- should Vulcan secede, he will be required to resign from Starfleet and return home, or forever sever ties with his homeworld.
Years later, a decades-old plot to destroy the Federation from within forces Ambassador Sarek from the bedside of his dying wife, Amanda. The ambassador's decision widens the long-standing rift between himself and Spock at a time when they must pool their resources together. While the Enterprise crew contends with Romulans, Klingons, and the mysterious Freelans, Sarek's only comfort comes from reading Amanda's journals, which reveal more about his human spouse, his son, and himself than he ever realized.