Star Trek (1967): S01E27 – The Alternative Factor


“The Alternative Factor” is the twenty-seventh episode of the first season of the American science fiction television series Star Trek.

In the episode, the crew of the USS Enterprise encounters a “reality jumping” madman.

It is the first Star Trek episode to deal with a parallel universe.


The Enterprise is rocked by an energy pulse. Science Officer Spock informs Captain Kirk that the gravity pull of the planet fluctuated to zero and says that the surrounding space seemed to momentarily “wink” out of existence.

Sensors locate a human presence on the planet that was not there before. Mr. Spock and Kirk beam down to the planet and find a one-man spacecraft. A dishevelled, bearded man named Lazarus appears and accidentally slips off a cliff. The man survives the fall but is injured, and Kirk has him beamed to the Enterprise for examination.

Back on the ship, Lt. Masters informs Captain Kirk that the mysterious disturbance has drained the dilithium crystals in the warp drive. A message from Starfleet reports that every quadrant has been subjected to the same winking effect and electronic disruption as the Enterprise. Starfleet fears that the disruption may be a prelude to an invasion and has ordered all ships except the Enterprise to leave the area. Kirk is ordered to find the cause of the disturbance.

Lazarus frequently fades in and out of the universe, encountering his look-alike enemy in a “dimensional corridor”, creating an energy wink, rippling through the universe. Spock reports a “rip” in space and time on the planet. Lazarus insists that his enemy, trying to destroy the universe, is causing the phenomenon. Lazarus demands dilithium crystals so he may fix his ship and continue to fight his enemy. Kirk refuses; Lazarus steals dilithium from the Enterprise and is caught. Lazarus denies the theft and blames it on his yet unseen nemesis.

Kirk beams back to the planet with Lazarus and a security team to seek this “hidden” enemy. Lazarus has another dimensional corridor episode and is returned to sickbay. Lazarus explains to Kirk that he is a time traveller; the planet below was once his home world. Lazarus claims his enemy destroyed his civilisation in the past, for which Lazarus has chased him for centuries.

Mr. Spock develops a hypothesis that Lazarus is two men, and his enemy is his counterpart from an anti-matter universe. If he and his anti-self contact each other within either physical universe outside the dimensional corridor, they would destroy each other and annihilate both the matter and anti-matter universes.

Lazarus slips away from sickbay and creates a diversion in engineering to acquire dilithium. With the stolen crystals, he beams down to the planet to repair his ship. Kirk follows, but Lazarus activates his time machine just as Kirk tries to stop him. Stepping into the portal, Kirk is accidentally teleported to the anti-matter universe, where he meets the Anti-Lazarus.

The Anti-Lazarus calmly admits to stealing the Enterprise’s dilithium. He also explained that the dimensional corridor was like a “safety valve” that protected the two universes from blowing up. He informs Kirk that his people believed two universes existed, and when his matter counterpart learned about it, he went insane and became obsessed with destroying him. He tells Kirk that only by destroying the ship with the two Lazaruses inside the dimensional corridor which links the two universes can both universes be saved. Kirk realises this would trap the two men in the corridor forever.

Kirk confronts the matter Lazarus, and pushes him into the dimensional door. Kirk heads back to the Enterprise, ordering the ship’s phasers to target the dimension ship. The two Lazaruses meet once more and fight inside the dimensional corridor as phaser beams vaporise the ship.

Star Trek TV Series

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Production & Filming Details

  • Director(s): Gerd Oswald.
  • Production: Desilu Productions (1966-1967) and Paramount Television (1968-1969).
  • Distributor(s): Paramount Pictures (1966-2006), CBS Paramount Television (2006-2007), and CBS Television Distribution (2007-Present).
  • Original Network: NBC.
  • Release Date: 30 March 1967.
  • Running Time: 50 minutes.
  • Country: US.
  • Language: English.

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