Autumn began and clouds fell on Pettson. Will the cat manage to cheer up Fiškus' grandfather?

Summer is irrevocably gone, it has gotten colder outside and the weather outside the window is gloomy. Grandpa Pettson is in a bad mood. He doesn't want to do anything — dig a potato field or chop wood, let alone play with Fiškus. He just sits at the kitchen table for hours, staring and grunting in displeasure.

Fiškus tries to distract Grandpa in every possible way and lure him to the lake to fish, but he does not succeed. Nothing applies to Pettson, not even when the cat stirs in a saucepan on the kitchen floor or shoves a line with a trophy fish tied to it in Grandpa's hand.

In the end, he decides to trick Grandpa and set a trap for him. But it wouldn't be Fiškus if he didn't come up with something! Will the cat manage to cheer up Pettson in the end?