Kirk and McCoy accompany Spock to the Vulcan Academy Hospital, seeking experimental treatment for a badly wounded Enterprise crew member. Spock's mother is also a patient in the hospital, and Kirk soon becomes involved in the complex drama of Spock's family.

Suddenly, patients are dying, and Kirk suspects the unthinkable -- murder on Vulcan. Kirk has to convince the Vulcans that something as illogical as murder is possible. Until the killer is caught, everyone is in danger.