A beginning Russian painter takes on a commission to paint a picture. The client, an attractive Swede, wants to immortalize his house on canvas—a house standing on the shore of Trollhol Island in the northwestern part of Sweden. The main condition is that the house must be painted from life. The painter arrives on the island and learns that there is an ancient fortress there, which was besieged by enemies many times, but never taken. The locals believe that the king who founded this fortress held the defense with the help of certain mystical beings—some kind of trolls, or perhaps other gigantic monsters. These creatures could sense those who came with the purpose of taking something—whether land, a house, or even someone’s heart. They say these powerful patrons still hide in the dungeons of Trollhol and protect the island from outsiders. The more the painter comes to like the owner of the house, the more acutely she feels the threat hanging over her.