A physicist working at an atomic research lab in New Mexico goes into work one day with a spider in his pants cuff. The creature is bombarded by the atomic rays and grows to a huge size, gaining the power to think and speak, and then attacks the humans. The physicist tricks the spider into snagging a test missile in its web and when it climbs towards it, the missile detonates and kills the spider.; A couple with a nasty landlord get a free TV set from a stranger. It is a device sent by aliens to enslave Earth by hypnotizing people through the sets in preparation for their landing force. The couple snap out of the hypnosis and the aliens from Pluto realize that their plan has failed and leave Earth. It turns out the landlord took down the antenna that the couple had set up to improve reception of the set, and the couple express their overwhelming gratitude to the puzzled landlord.; Martians come to Earth to discover if humans represent a threat to them. They question a human using a machine to verify his answers, and find that he is totally free of greed, hatred or deceit. The Martians leave satisfied, unaware that they questioned a mental patient.; A couple moves to a cursed castle and the man discovers the imprisoned Medusa. When her powers do not affect him she thinks they have disappeared and accidentally turns herself to stone, not knowing the man is blind.