The story is set on the (fictional) island of Hemsö near Stockholm. Mrs. Flod, a wealthy widow, hires Carlsson to run the farm. He is not an islander but a newcomer, and the locals distrust him. Carlsson's main opponent is Gusten, Mrs. Flod's son and heir: a struggle for power ensues between them. Is Carlsson now an impostor trying to exploit a lonely widow, or an honest, hard-working man trying to breathe new life into the farm?