Donald Morris, wealthy 'man about town', has fallen madly in love with mysterious stage actress Mary Blake. As the story begins, Donald has professed his love and asked Mary to be his wife. Despite her obvious feelings for him, Mary cannot accept and soon disappears from her apartment, where she lives with her twin sister, Anne, who has also vanished. Mary has sent Donald a cryptic note that leaves Donald frantic. He hires the highly recommended detective, Peter Clancy, to help him find Mary. There is blood and disarray in the apartment. Anne is seen leaving with a huge trunk. Where is Mary? Where is Anne? What has happened?
Clancy and his partner O'Malley are skilled investigators with prior careers in law enforcement. Clancy forms a close relationship with Morris, which is unusual for the time given their different backgrounds and social status. The writer, in passing, shows the listener some of the biases of the time against immigrants. Clancy and several of his agents are of Irish descent and, having risen in status, make derogatory remarks about foreigners in general and specifically about the Italian janitor who works in Mary's apartment building. While perhaps unpleasant to the modern listener, the comments reflect the times and add color to the story.
Clancy is tireless in his pursuit and examination of Mary's life. Each chapter adds a detail, frequently unrecognized for its importance until much later. Thayer, the artist, is slowly and methodically building up her canvas.
Finally, Clancy triumphs! All is revealed and the clever listener will exclaim "Aha! I thought so!" while still being amazed at the author's mastery of the genre.
