Mister Rogers brings an empty, smelly milk carton to make a paddle wheel boat and then demonstrates how it works.In the Neighborhood of Make-Believe, Robert Troll and Cornflake S. Pecially stain a chair. Corney tells Robert to dump the excess stain in the creek. The stain pollutes the water. King Friday and Queen Sara notice a bad smell at the castle. King Friday sends Donkey Hodie and Robert Troll to find the source of the smell. Robert and Corney explain to the king that the pollution started at the factory. The king tells Corney not to manufacture anymore until he finds a clean way to do it. Mister Rogers uses part of a milk carton to make a garage and a second paddle wheel boat. He then uses water that he has been floating the boats on to water plants. While doing this, Mister Rogers talks about how Corney felt when the king scolded him for making a mess.