Budd Albright

Dr. Leonard "Bones" McCoy meets a former girlfriend when the Enterprise brings supplies to a remote archaeological survey group. Still attractive to McCoy, the woman's current appearance and her colleague hide a deadly secret, ultimately revealed as a tragedy of ecology.

Viewers are introduced to Nurse Christine Chapel in this story as she signs aboard the crew to search for her missing fiance, the brilliant Dr. Korby. He turns up on Exo III, oddly working on a plan to create android duplicates of key figures, beginning with James Kirk — until the captain sabotages his duplicate to alert Spock.