After dreaming that her alter-dimensional sister Sobak was in danger, Anna Rykov is sent to Depression era Boston to find and kill the shape shifting alien who has captured her, and whose plans could bring about the extinction of all life on Earth. Anna is assisted by Cletus the hound and a homeless a World War I veteran with skeletons in his own closet. However, Anna's inquiries catch the attention of J. Edgar Hoover, whose motives in this case are unknown.