Star Date 4373.5 - The Enterprise is en route to the planet Elas when they receive a distress call from the planet Troyius. Ambassador Petri is on board and has been charged with escorting a Troyian princess, Elaan, to the planet Elas. Elaan is to be betrothed to the Elasian ruler to end the war between the two planets. Upon arriving at Troyius, the crew discovers that Elaan is a Dohlman, a woman with great powers of enchantment. Unfortunately, she has been targeted by a rival Troyian faction hoping to prevent her from reaching Elas. The Enterprise crew is attacked by a group of Klingons, who the faction has hired. The Enterprise is damaged in the midst of the fight, though they eventually manage to drive the Klingons away.

The crew then begins their journey to Elas, but Elaan's enchantment causes chaos on the ship. She has a temper tantrum and tries to force Kirk to marry her. Kirk realizes that Elaan is manipulating him and refuses. Meanwhile, the Troyian agent sent to accompany Elaan has betrayed the Enterprise and has contacted the Klingons to set up an ambush. The Klingons attack the Enterprise again, and the crew is forced to fight them off.

The crew manages to escape the Klingons and reach Elas, where Elaan is finally betrothed to the Elasian ruler. The episode ends with Elaan expressing her gratitude to Kirk for his help.

The lead actress in this episode was France Nuyen, who plays Elaan. Nuyen had previously appeared in several 1960s films and television shows, including The Manchu Eagle Murder Caper Mystery and The Wackiest Ship in the Army. After her appearance on Star Trek, she appeared in other television shows and films, including Falcon Crest and The Joy Luck Club.

This episode was filmed on the same set as Elaan's spacecraft, which had been used in the episode "The Apple" from the same season. The Troyian agent in this episode, Aris, was played by John Winston, who had previously appeared as Lt. Kyle in "The Menagerie." This episode was the first to feature the character of Aris, and he would go on to appear in several other episodes throughout the series.