 The ferry-boat from Stockholm arrives at the island Saltkråkan in the Stockholm Archipelago. Among the passengers are the widower Melker Melkersson and his four children, Malin, Johan, Niklas and Pelle. Malin, who is grown up, acts as a mother for her little brothers. The family has bought a summer-house on the island. When they arrive they find out that the house is in bad condition and the roof leaking. Their closest neighbours are the Grankvist family, who runs the shop on the island. Nisse and Märta Grankvist have three daughters, Teddy, Freddy and Tjorven, who are in the same age as the three boys in the Melkersson family.