Lum and Abner finally solved the mystery of how Grandpap could tell what was in the unlabelled canned goods on the shelves of the Jot 'Em Down store. He merely looked at the big anniversary picture they had hanging up in the store, which showed the canned goods section before Cedric had washed the labels off and Grandpap knew that Cedric had put the can back in the same order. But Lum and Abner have now switched the cans around and are waiting in the store to play a trick on Grandpap...