Inspector Maria Vern comes on vacation to the island of Gotland. But instead of an easy part-time job in the local police, along with relaxation by the sea and walks around ancient Visby, hot days await her and her colleagues: the body of a recently murdered man was discovered in an ancient stone mound. The late Wilhelm Jacobson, as it turns out, was a difficult man. But who would want his death? And is there a connection between it and two other murders, the mysterious marsh lights over Martebu and the legendary silver of a medieval Danish king?