Meanwhile, Communications Officer Lt. Uhura has detected an encoded transmission beamed from "Enterprise" to a fast-moving vessel at the extreme edge of sensor range. Shortly afterward, Ambassador Gav is found murdered, his neck broken by what Spock describes as an ancient Vulcan method of execution called "Tal-Shaya", casting suspicion on Sarek. During questioning, Sarek suffers a cardiovascular event, and is rushed to the sickbay, where Chief Medical Officer McCoy determines that he requires immediate surgery. Because there is a shortage of his rare T-negative-type blood, Spock volunteers to donate some of his own blood for the operation, using an experimental stimulant for increased blood production.