Fed up with the noise of the traffic outside his house, Mr Benn heads off for the costume shop. Putting on a caveman’s animal skin, he steps into a prehistoric land and meets a tribe of cavemen sheltering inside some cramped caves. Just as Mr Benn asks why they do not sit on the grass outside, he narrowly avoids being trampled into the ground by a hoard of stampeding dinosaurs. When the cave people explain that they have to put up living in the caves because there is nowhere else to live, Mr Benn decides to give the tribe a lesson in building construction…
