A misguided scientist enables an alien from Venus named Zontar to come to earth in order to "help solve man's problems". However, as soon as Zontar arrives on Earth, it quickly becomes obvious that the three-eyed, bat-winged, skeletal black creature has a hidden agenda.

Tommy Kirk leads his fellow Martians to Earth on an interplanetary quest for females. Kirk proves that Martians have impeccable taste when one of his first conquests turns out to be sexy scientist Yvonne Craig.