A Random

SCIFI.radio story

Earth encounters a group of time-traveling tourists on a sightseeing trip to the past who want to plug us into a power grid and use us as living batteries even though they are only slightly radioactive and might be overpowered by a slap to the side of the head with a large fish , but scientists create a new weapon which kills them all.
The End.and then they kill us all.
The End.