Star Trek - The Original Series

Kirk becomes embroiled in an alien race's plot to reduce the population of its planet by infecting people with a lethal plague. S3, Ep16/24

The crew is stranded on a hostile planet and find themselves stalked by a beautiful woman who can kill people just by touching them. S3, Ep17/24

En route to the Federation archives at Memory Alpha, the Enterprise encounters a strange energy field which takes over the mind of a lieutenant aboard the ship. S3, Ep18/24

When a plague sweeps through the Enterprise, the crew head to a nearby planet to search for an antidote, where they meet an immortal being and his daughter. S3, Ep19/24

The Enterprise is hijacked by a group searching for the idyllic planet of Eden, but Kirk is stunned to learn the truth about the supposedly blissful paradise. S3, Ep20/24