Sherlock Holmes and Dr. Watson are called to investigate the abandonment of Miss Mary Sutherland at the altar on her wedding day. The woman, a nearsighted typist, has a substantial income from the interest on a fund set up for her, and had become engaged to a quiet Londoner, Hosmer Angel, whom she met at a ball. He was a peculiar character, rather quiet and secretive about his life, and during his periods of absence, had asked her to write to him, addressed only to a post office at Leadenham Street.