Humphrey Challoner is a solitary old man who spent a lifetime collecting for his private museum, primarily mammals exhibiting osteological abnormalities but also 24 articulated human skeletons without any apparent defect. His friend, Dr. Wharton, is puzzled by the collection, but he humors Challoner's eccentricities and tends to him in his final illness. When Wharton inherits the collection on Challoner's death, the dark mystery that ties the collection together is finally revealed.