Summer, 1939. On an isolated, rocky island in the Baltic Sea, lighthouse keeper Master Hasselbond is a God-like figure, overseeing his despairing wife, an innocent young daughter and a teenage son, Gustaf, who both fears and loves him. Then an outsider arrives -- a 13-year-old boy chosen by default to become the lighthouse keeper's assistant much to Hasselbond's disgust. Raised and abused in an orphanage, Karl is determined to prove his worth. He befriends Gustaf, but their friendship changes to rivalry and hate when Hasselbond starts to favor Karl over his own son.