As it appears the Enterprise’s captain is lost exploring a stranded Starfleet vessel, the Federation’s flagship comes under siege from an alien race.
“The Tholian Web” is the 9th episode of the 3rd season of the original Star Trek series. Written by Judy Burns and Chet Richards and directed by Herb Wallerstein and Ralph Senensky, it first aired on NBC on November 15th, 1968.
In the episode, the Enterprise has found their lost sister ship, the USS Defiant, which seems to have suffered a deadly mutiny. Suddenly, the Defiant begins disappearing while some of the Enterprise’s crew is onboard. Everyone makes it off, but Kirk, who has temporarily been transported to another universe. As they try to find a way to get their Captain back, the Enterprise’s crew becomes trapped in the sinister web weapon of the Tholians.
The Tholians make their first appearance here and would later be mentioned several times throughout the Star Trek canon. The story of the USS Defiant and the universe it disappeared too would be followed up on in the Mirror Universe-set “In a Mirror Darkly,” a fourth-season episode of the series, Enterprise.