AllMovie

Investigating the disappearance of the starship Defiant, the Enterprise finds the vessel drifting with a dead crew, who apparently killed each other in a fit of communal madness. Captain Kirk beams aboard the Defiant to investigate but becomes stranded due to a transporter malfunction; indeed, he is still on board when the ship vanishes into another dimension. In Kirk's absence, the Enterprise is attacked by a ship of Tholians, who create an energy-based "web" to trap the ship. Meanwhile, the crew of the Enterprise appears to be falling victim to the same madness that destroyed the Defiant. This episode of the popular science fiction series centers on the attempts of Mr. Spock -- left in command of the Enterprise -- to rescue Kirk and free the ship from the Tholian web, while dealing with an increasingly insane crew.