Aired: 9/8/1966
Dr. McCoy discovers his old flame is not what she seems after crew members begin dying from a sudden lack of salt in their bodies.
Aired: 9/15/1966
Captain Kirk must learn the limits to the power of a 17-year-old boy with the psionic ability to create anything and destroy anyone.
Aired: 9/22/1966
The flight recorder of the 200-year-old U.S.S. Valiant relays a tale of terror--a magnetic storm at the edge of the galaxy.
Aired: 9/29/1966
The crew is infected with a mysterious disease that removes people's emotional inhibitions to a dangerous degree.
Aired: 10/6/1966
A transporter malfunction splits Captain Kirk into two halves: one meek and indecisive, the other violent and ill tempered. The remaining crew members stranded on the planet cannot be beamed up to the ship until a problem is fixed.
Aired: 10/13/1966
The Enterprise picks up untrustworthy entrepreneur Harry Mudd accompanied by three beautiful women who immediately put a spell on all the male crew members.
Aired: 10/20/1966
Nurse Chapel is reunited with her fiancé; but his new obsession leads him to make an android duplicate of Captain Kirk.
Aired: 10/27/1966
The Enterprise discovers a planet exactly like Earth, but the only inhabitants are children who contract a fatal disease upon entering puberty.
Aired: 11/3/1966
Kirk and psychiatrist Helen Noel are trapped on a maximum security penal colony that experiments with mind control and Spock must use the Vulcan mind-meld to find a way to save them.
Aired: 11/10/1966
After the Enterprise is forced to destroy a dangerous marker buoy, a gigantic alien ship arrives to capture and condemn the crew as trespassers.
Aired: 11/17/1966
Spock kidnaps the disabled Capt. Pike, hijacks the Enterprise, and then surrenders for court martial.
Aired: 11/24/1966
At Spock's court martial, he explains himself with mysterious footage about when Capt. Pike was kidnapped by powerful illusion casting aliens.
Aired: 12/8/1966
While Captain Kirk investigates whether an actor is actually a presumed dead mass murderer, a mysterious assailant is killing the people who could identify the fugitive.
Aired: 12/15/1966
The Enterprise must decide on its response when a Romulan ship makes a destructively hostile armed probe of Federation territory.
Aired: 12/29/1966
The past months have left the crew exhausted and in desperate need of a break, but does this explain McCoy's encounter with a human-sized white rabbit or Kirk crossing paths with the prankster who plagued his days at Starfleet Academy?
Aired: 1/5/1967
The Galileo, under Spock's command, crash-lands on a hostile planet. As the Enterprise races against time to find the shuttlecraft, Spock's strictly logical leadership clashes with the fear and resentment of his crew.
Aired: 1/12/1967
A being that controls matter and creates planets wants to play with the Enterprise crew.
Aired: 1/19/1967
For bringing hostility into their solar system, a superior alien race brings Captain Kirk into mortal combat against the reptilian captain of an alien ship he was pursuing.
Aired: 1/26/1967
The Enterprise is thrown back in time to 1960s Earth.
Aired: 2/2/1967
Kirk draws a court martial in the negligent death of a crewman.
Aired: 2/9/1967
Seeking the answer to a century-old mystery, Kirk and crew encounter a vacantly peaceful society under a 6000-year autocratic rule that kills all those it can't absorb.
Aired: 2/16/1967
While on patrol in deep space, Captain Kirk and his crew find and revive a genetically-engineered world conqueror and his compatriots from Earth's Twentieth Century.
Aired: 2/23/1967
Kirk and Spock must save their ship's crew when they are all declared killed in action in a bizarre computer simulated war where the actual deaths must nevertheless occur.
Aired: 3/2/1967
The Enterprise investigates a planet whose colonists should be dead, but are not.
Aired: 3/9/1967
The Enterprise is sent to a mining colony that is being terrorized by a mysterious monster, only to find that the situation is not that simple.
Aired: 3/23/1967
With a war with Klingons raging, Kirk and Spock attempt to resist an occupation of a planet with incomprehensibly placid natives.
Aired: 3/30/1967
Existence itself comes under threat from a man's power-struggle with his alternate self, with the Enterprise's strained dilithium crystals presenting his key to a final solution.
Aired: 4/6/1967
When a temporarily insane Dr. McCoy accidentally changes history and destroys his time, Kirk and Spock follow him to prevent the disaster, but the price to do so is high.
Aired: 4/13/1967
The Enterprise crew attempts to stop a plague of amoeba-like creatures from possessing human hosts and spreading throughout the galaxy.
Aired: 1/22/1965
Capt. Pike is held prisoner and tested by aliens who have the power to project incredibly lifelike illusions.
