The Dutch newsreel service Polygon-Journal
gathered journalists to inform them about an "astonishing discovery from 5000 BC." An amateur filmmaker had found a hole in the side of a hill outside the village of Klimmen, in the province of Limburg. The hole led to a cave system that appeared to have been the home of prehistoric men.
After being shown some of the artifacts found in the cave, journalists were led inside it. They made their way through a maze of corridors, past inscriptions carved into the limestone walls. At last, they reached an inner room, in which they found a mysterious metal box.
The box was dragged outside. When opened, there was a chunk of limestone inside of it. One of them lifted the rock into the air. As he raised it up, everyone could see the single phrase that was carved into it: "1 April"