 The telepath manages to partially restore the Guardian's timetravel functions but collapses in a comatose state.Using the Guardian, Kirk, Spock, and Dr. McCoy travel into the past of the planet Sarpeidon to find Zar, hoping that his powerful telepathy combined with Vulcan shield training will allow him to successfully restore the Guardian to its normal state.They find Zar in charge of a small, technologically advanced settlement that is about to engage in a battle with an alliance of less advanced but more numerous enemy clans.