Star Trek (1968): S02E20 – Return to Tomorow


“Return to Tomorrow” is the twentieth episode of the second season of the American science fiction television series Star Trek.

Written by John T. Dugan (under the pen-name “John Kingsbridge”) and directed by Ralph Senensky, it was first broadcast 09 February 1968.

In the episode, telepathic aliens take control of Captain Kirk, Dr. Ann Mulhall (Diana Muldaur), and First Officer Spock’s bodies in order to construct android hosts.

This episode was the first appearance of Diana Muldaur in the Star Trek franchise. She appeared again as Dr. Miranda Jones in the third season episode, “Is There in Truth No Beauty?” and as Dr. Katherine Pulaski in the second season of Star Trek: The Next Generation.


The starship Enterprise receives a distress call from a lifeless planet. Upon arrival, a telepathic being named Sargon (voiced by James Doohan) addresses Kirk and Spock as his “children”, and invites them to beam down to the planet. Kirk, Spock, Dr. McCoy, and Lt. Cmdr. Ann Mulhall beam to a subterranean vault where the voice of Sargon greets them from a luminous sphere on a pedestal.

Sargon explains that he and two others are the last survivors of their race; their minds, stored in these spheres, have existed here since their planet was devastated by war. Sargon then transfers his mind into Kirk’s body and Kirk’s mind into the sphere. Sargon explains that he and his companions will need human bodies temporarily, in order to construct android hosts for themselves, and then returns to his orb. Kirk, returned to his own body, declares his confidence in Sargon.

Back onboard the Enterprise, the four meet with Chief Engineer Scott to consider Sargon’s request, and Kirk convinces the others with a rousing speech about risk. The spheres of Sargon, his wife Thalassa, and his former enemy Henoch, are brought up from the planet. McCoy supervises as Sargon takes Kirk’s body again, and Thalassa and Henoch take Mulhall’s and Spock’s bodies, respectively. When Sargon and Thalassa become exhausted by the strain of the transference, Henoch instructs Nurse Chapel in preparing a serum that will strengthen the host bodies. Chapel notices that the serum in the hypospray designated for Kirk does not contain the correct formula. Henoch confesses that he intends to kill Kirk, and Sargon with him, in order to keep Spock’s body. Henoch then erases Chapel’s memory of the conversation.

Manufacture of the android hosts begins. Kirk’s body weakens more quickly than the others, requiring additional doses of the serum. Henoch tries to tempt Thalassa into keeping their hosts’ bodies, because the android forms will be incapable of sensuality. She in turn tries to convince Sargon, but he collapses. McCoy declares that Kirk’s body has died and Sargon is gone. Back in sickbay, McCoy is able to revive Kirk’s bodily functions, but has no way to restore Kirk’s mind. Thalassa offers to restore Kirk in exchange for McCoy’s help in keeping Mulhall’s body. When McCoy refuses, she assaults him telepathically, but then has a change in heart and relents. The voice of Sargon commends her, and she realises that Sargon is using the ship itself as a temporary body. She then informs McCoy that Sargon has a plan, and locks him out of the examination room, after which Chapel marches out of sickbay. McCoy reenters the examination room and finds that Kirk and Mulhall have been returned to their bodies. However, the spheres have been destroyed, including the one that held Spock’s mind. Kirk says that this was “necessary”, and asks McCoy to prepare a lethal hypospray for Henoch.

Henoch, who has taken control of the bridge and is terrorising the crew, reads McCoy’s mind and prevents the injection. Henoch then commands Chapel to use the lethal compound on McCoy. She moves as if to comply, but then injects Henoch instead. Henoch boasts that he can transfer to another body, but finds he cannot due to interference from Sargon. Henoch pleads for mercy, but Spock’s body collapses, seemingly in death.

Sargon tells Kirk that he could not allow this. Spock’s and Chapel’s bodies glow, and Spock revives. Sargon reveals that the injection was not lethal; it was important for McCoy and Chapel to believe it was lethal so that Henoch would believe it also. Spock’s mind had been temporarily placed in Chapel’s body.

Sargon and Thalassa announce that they will not attempt to build host bodies, but will “depart into oblivion” instead. They make a final request: to be allowed to use Kirk and Mulhall’s bodies one last time to share a kiss.

Star Trek TV Series

You can find a full index of Star Trek TV series here.

Star Trek TV Series, Films, and Documentaries

You can find a full index of all Star Trek TV series, films, documentaries here.

Production & Filming Details

  • Director(s): Ralph Senensky.
  • Writer(s): John T. Dugan.
  • 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: 09 February 1968.
  • Running Time: 50 minutes.
  • Country: US.
  • Language: English.

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