The once-great captain Garth of Izar took over the Elba II asylum for the criminally insane and tried to take the Enterprise, using his ability to change shape.
In 2269 Kirk and Spock delivered a new drug to the asylum on Elba II, where Garth of Izar had seized control from Governor Donald Cory. Garth had been a decorated starship captain, but after learning to change shape from the Antosians, he became mad and was committed. He styled himself master of the universe and planned to use the Enterprise to begin a war of conquest.
Garth took Kirk's form and tried to trick the crew, and he killed the inmate Marta. Scott refused to beam anyone up without the right countersign. Spock told the two Kirks apart, and Garth was treated with the new drug.