Spock's mother, Amanda Grayson, is dying, and Spock returns to the planet Vulcan, where he and Sarek enjoy a rare moment of rapprochement. But just as his wife's illness grows worse, duty calls Sarek away - once again sowing the seeds of conflict between father and son. Yet soon Sarek and Spock must put aside their differences and work together to foil a far reaching plot to destroy the Federation - a plot that Sarek has seen in the making for nearly his entire career.