The famous jazzman Carlos Rivera was shot dead during a concert. And it so happened that Inspector Roderick Alleyn was among the spectators during the commission of the crime! But who is the killer? Lord Pastern-and-Baggott, who did everything to promote Carlos’s jazz band, and in return received only black ingratitude? The lord’s stern wife, Lady Cecil, who discovered that Rivera is having an affair with her daughter, the beautiful Felicite? Or someone else from the many enemies and envious people of the famous musician?