    Stapleton already escaped when he heard the gun's shooting. His wife never liked to do those bad things with her husband. She had sent a letter of warning when Sir Henry reached London. Later on, she persuaded Henry to keep away from the place many times. Now she would rather not escape with her husband. So Stapleton tied her to a pillar in her house. When Holmes released her, she denounced her husband's wicked conduct. She also helps Holmes to find the secret places for Stapleton to hide and train the hound. There were a lot of tools over there, including phosphorus powder to be coated on the hound for strange light.
The mystery of the Hound of the Baskervilles was finally revealed. Unfortunately, Stapleton did not receive the court's trial before he was drowned in the mire. 
