When Minka leaves to visit his older sister Lyolya, now a grown woman with 6-year old twins Petya and Fedya, everything on the journey reminds him of funny stories from their childhood past. What he does not know is that the twins' prank has put Lyolya in serious trouble. And only Minka's arrival and the neighbour's steam engine can save Lyolya from prison. Based on children stories by Mikhail Zoshchenko.