Murder by an Aristocrat

Bayard Thatcher is blackmailing the family into which he has married. He demands $25,000 by the next night or else he will tell about shady deals and family skeletons. That is the price the bully Bayard demands for leaving the family alone. At Midnight, he is shot and Dr. Carick is called. He has nurse Keating take care of Bayard's superficial wound and watch over him. Later that night, a mysterious person steals the gun under his pillow as he is out arguing with someone. He is still alive in the morning and demands the money before nightfall, but he does not live long enough to claim it. Who did him in? Sally Keating has some clues and a lot of questions.