Murder Mansion - Herman Landon

THE STORY: Donald Chadmore, newly released from prison for an assault charge has come to his uncle Theodore's home in order to protect him from a possible attack. He takes his uncle to the library at the ancient gloomy Chadmore home known to locals as "Mystery Mansion" and locks both of them inside. The heavy door is bolted twice and locked from the inside. All windows are barred. There is no way anyone can get inside. And yet spectral music plays from the piano in the corner of the library and a shadowy figure emerges from the darkness. Uncle Theodore cries out to Donald. Donald fires his revolver at the shadowy figure. He goes to the divan where his uncle was sitting but it's empty. Uncle Theodore is found behind the furniture piece on the floor. He's been shot. Not only shot but stabbed with an antique dirk that Donald had handled only a few hours ago and which was left in the hands of someone now locked upstairs in the attic. Who was the shadowy figure and how did it get in to…