AllMovie

Ordered to evacuate a planetary colony that is under the threat of deadly radiation, Captain Kirk faces unexpected resistance when the settlers claim they have no desire to leave. When Kirk, McCoy, and Spock investigate further, they discover that the colony's inhabitants are both perfectly healthy and oddly blissful. The reason for this behavior becomes clear when McCoy and Spock unintentionally inhale the spores of a native plant, and become seized with the same contented lethargy. The spores' effects spread when several of the plants are brought aboard the Enterprise, and Kirk must find a way to win back his crew before the ship and planet are destroyed in this installment of the landmark science fiction television series.