The Abandoned Room

Who killed Silas Blackburn? On the eve of the day that he planned on removing his grandson from his will, Silas Blackburn goes to bed in the abandoned room where many of his family have died in agony. In the middle of the night he is found dead in this locked room. How did someone get into the room? And who? Bobby, the grandson, has the motive and due to drinking can't remember his actions on that night...