Andrew Ferguson travels to Roseland, a remote island in the southern Atlantic, to research why an unusual bird, the Roseland Auk, has many more males than females. Back in the States, his professor warns him that the island’s society is matriarchal, it retains pagan customs, and the women are off limits to outsiders. He ignores the professor’s advice and falls for a beautiful islander, who is promised to the son of the Penseythan, the island’s head. Through his research, Andy understands the bird’s behavior and uncovers the islanders’ dark secret. When he ignores the Penseythan’s warnings to stop meddling in the island’s affairs, he puts his life in danger.