Star Trek TOS - Emotions

Episode - Where No Man Has Gone Before

When the Enterprise attempts to penetrate a space barrier, it is damaged and creates a potentially worse problem. Two crew members, including Kirk's best friend, gain psionic powers that are growing exponentially. This leaves Captain Kirk with the difficult choice; either marooning them or killing before they get so powerful they lose their humanity and become truly dangerous.

William Shatner - Capt. Kirk,
Leonard Nimoy - Mr. Spock,
Gary Lockwood - Lt. Cmdr. Gary Mitchell,
Sally Kellerman - Dr. Elizabeth Dehner,
George Takei – Sulu,
James Doohan – Scott,
Lloyd Haynes – Alden,
Andrea Dromm - Yeoman Smith,
Paul Carr - Lt. Lee Kelso,
Paul Fix - Doctor Piper,