A distress call from Lt. Noonien-Singh compels Spock to disobey orders and take the U.S.S. Enterprise and its crew into disputed space, risking renewed hostilities with the Klingons in a bid to aid their shipmate.

La'an travels back in time to twenty-first-century Earth to prevent an attack which will alter humanity’s future history—and bring her face to face with her own contentious legacy.