The action takes place in Sweden at the beginning of the 20th century. Rasmus is a boy who lives in a shelter. Not content to stay under the strict discipline of the orphanage, he escapesand joins a tramp, nicknamed "Oscar Tumbleweed. They begin to travel the country together, but Oscar is constantly trying to find parents for the boy. Rasmus harassing Oscar, does not want to leave him. During their journeys they are able to solve a crime and recover the valuable painting of missis Frou Hetbert. Summer ends, and it's time to look for a place to spend the winter. Oscar and Rasmus arrive at the farm of a good hostess, Martina...