German schoolboy Matti (10) generally takes care of doting kid brother Sami as their Finnish father, bus driver Sulo Pekkanen, is an absent dreamer, their German housemother Annette a useless whiner, only cool maternal uncle Kurt really helps and counsels the kids. Classmate Turo convinces Matti a summer holiday abroad may be the solution. After a parental row over Sulo's alleged Swiss holiday cabin, Matti decides to attempts 'fixing flaws in the universe'. One lie leads to another trick, till his parents believe they won a house in Finland and decide not to just to spend the Sumer holiday there, but resign from work and sell the house, even wreck furniture, to move there. They erroneously get the key, but soon find the house belongs to one Mr. Markku Virtanen, leaving them homeless without income. Father swallows his pride to ask his boaster brother Jussi Pekkanen for help, thus discovering uncle only faked wealth, yet things work out.
—KGF Vissers