Chekov's Attack (The Tholian Web)

Back on the bridge of the Federation starship USS Enterprise, Commander Spock explains that Captain Kirk has slipped into another universe. He has determined that an interphase occurs for short periods in which one may travel between universes occupying the same point. In two hours, the computer calculates, another interphase will occur. However, the Enterprise must not expend any energy or the dimensional rift will be damaged and Kirk will be lost forever. During this explanation, Chekov becomes enraged. He leaps up, pushes Spock away, and, screaming, attacks Sulu. Scotty grabs him and Dr. McCoy arrives to help. Spock grabs Chekov's face. Then, Spock uses the Vulcan nerve pinch on Chekov, knocking him out. Security officers then arrive on the bridge and Scott and the security officers take Chekov to sickbay.