Women on a distant planet drain the life of male crews, and the female crew take command.
Investigating ships that vanish every 27 years in the Taurean system, the Enterprise is drawn to a planet by a musical signal that clouds the men's judgement. Kirk, Spock, McCoy and a crewman beam down and are entertained by beautiful women, but headbands they are given drain their life force, and they age rapidly.
With the male officers affected, Lieutenant Uhura takes command and leads Nurse Chapel and a female security team to the surface. The women explain that they survive by draining male visitors. The men are rescued and restored with their stored transporter patterns, and the women agree to be taken to a new home. Margaret Armen wrote the episode.