简要：Twenty years ago, Mrs. Barlow was killed in her home at 12 Pimlico Square for her priceless ruby. The murderer searched the entire house but couldn't find them before disappearing. Since then, the house has been empty, but now Paul and Bella Mullen have moved into the apartment. Bella Mallen suffers from forgetfulness and nervousness, at least that's what her husband told her. B. G. Rough is an elderly horse herder who served as a police officer 20 years ago and still remembers this unresolved case. He noticed that Mr. Mullen looked like Mrs. Barlow's nephew Louis Barre. Why does Mr. Mullen leave so mysteriously every night just to go to apartment 14 next door?
