鼠洞里的好朋友，携手共度每一刻。美足小说

　　7-year-old Bertil's parents are at work and Bertil are home alone and bored. He is the only child in the family since his sister Martha died of an illness. But everything changes when he meets little Nils Karlsson Pyssling and they become friends. Nisse who lives in the basement in a room he rents from the rat Tjofsan,wich is cruel.