The Brown Mask is a mystery novel written by Percy J. Brebner. The story revolves around a man named John P. Dunster, who is a wealthy businessman and a member of the British Parliament. Dunster is known for his philanthropy and his support of various charitable causes. However, when he is found dead in his office, the police begin to investigate his death. The investigation is led by Inspector Burnley, who is assisted by his friend, Sergeant Long...