The narrative opens amid theatrical Broadway life and follows the investigation of a violent crime that disrupts a circle of actors and managers. A detective and his associates gather evidence—warning letters, costume details, a conspicuous woman in purple, and a lost clew—reconstructing scenes and checking alibis. They interview performers such as Kitty Legaye and Miss Templeton, pursue blind trails and false leads, and piece together hidden motives and secret correspondences until the central mystery is methodically resolved.