Beamed up during an ion storm, which causes a transporter malfunction, the landing party of Kirk, McCoy, Scotty and Uhura find themselves in a mirror universe aboard a parallel Enterprise run by ruthless barbarians. The ion storm also caused their malicious counterparts to beam to the real starship. Kirk and the others must find a way home before they are discovered and exposed by their parallel crew members, who use treachery, back-stabbing and seduction to get what they want.
Did You Know?
The only time in the series when someone replies to Doctor McCoy's "I'm a doctor..." line. McCoy says "I'm a doctor, not an engineer." Scotty answers, "Now, you're an engineer." See more
When the landing party is in the middle of the cross-universe transfer, the USS/ISS Enterprise is seen in orbit going in opposite directions (USS Enterprise going counterclockwise [when viewed from above]; ISS Enterprise going clockwise). However, through the rest of this episode, the ISS Enterprise is going counterclockwise. See more
Terror must be maintained or the Empire is doomed.
Special Enhanced version Digitally Remastered with new exterior shots and remade opening theme song See more