Larsson's father told him he cursed the day he was born. The family lived in extreme poverty in Gamla Stan, the old town of Stockholm. His father was a casual labourer who drank. The boy was admitted to the Royal Swedish Academy of Arts at thirteen, on the recommendation of a teacher who saw something in him that the household did not.

He struggled for years, working as an illustrator and retoucher of photographs while trying to establish himself as a painter. In 1882, at an artists' colony in Grez-sur-Loing outside Paris, he met the artist Karin Bergoo. They married, and everything changed. The watercolours he began painting in Grez were lighter, more fluid and more personal than anything he had produced before.

In 1888 Karin's father gave them a small house called Lilla Hyttnas in Sundborn, a village in Dalarna. The house became their joint project: Carl painted it, Karin designed the interiors, the furniture, the textiles, the colour schemes. The result was one of the most influential domestic interiors in Scandinavian design, a prototype for what would eventually become Swedish modernism. He painted the house and the family inside it (they had eight children) in watercolours that were published as a book, Ett Hem (A Home), in 1899. It sold across Europe.

The paintings of Sundborn are warm, bright and apparently effortless, which made people assume his life was too. It was not. He suffered depression in his later years and had a stroke in 1919. His most ambitious painting, Midvinterblot, a monumental canvas of a Viking midwinter sacrifice, was rejected by the National Museum. He admitted in his memoirs that the pictures of his family and home had become the most lasting part of his work. He was right.