Star Trek - Time for Yesterday

About “Star Trek - Time for Yesterday”

Time in the galaxy has stopped, indicating the Guardian of Forever is malfunctioning. Starfleet Command sends Admiral James T. Kirk, Spock of Vulcan, and Dr. Leonard McCoy on a mission to contact the Guardian. Their journey takes them 5,000 years into the past, where they must find Spock's son, Zar, to communicate with the Guardian. Zar is involved in his own struggles, and the trio must work to save both their world and his. The story is a 1988 novel by A. C. Crispin.