Ellis, an English barrister, goes to a hotel, in answer to a note of appeal, to rescue a woman he had formerly loved from the influence of her husband, a crook, who mistreats her. He takes her safely away, but shoots and wounds Gray, her husband. They flee, followed by threats of vengeance from Gray. Parr, an adventurer, occupying the room adjoining, has, unseen, witnessed the shooting affray. Ellis flees with Gray's wife for America. On the first day out she dies in childbirth and pleads with him to adopt her babe. Ellis agrees. Parr, who happens to be on the same ship, knows of the death of the mother and the adoption of the child. Ellis is ignorant of Parr's identity. Years later Ellis, happy with his ward, Betty, is in a secluded old mansion in America. He has never learned for certain whether or not Gray died and he is continually haunted by the thought that Gray might return. Parr, now an unscrupulous land dealer, visits Ellis's estate in an effort to purchase acreage which he knows to be rich in ore. He is astounded to recognize in Ellis the man whom he had seen shoot Gray 18 years before. Ellis flatly refuses to sell. Parr, angered, leaves, ready to employ a scheme to make Ellis leave the estate or sell it. Soon after, Betty is plunged into a state of constant fear by the growing terror of her old guardian. Betty sees and hears of a mysterious, ghostlike figure at nights and becomes convinced that her guardian is the victim of a frightful apparition, or fiend in human flesh. Nervous to the point of hysterics, she writes her guardian's young attorney, Briggs, to come to the mansion at Lone Willows. Briggs arrives, hears the strange story of the secret of the mansion, and resolves to stay until he has exposed the mysterious agent. He is not only unsuccessful, but in time becomes a haunted wreck, in as pitiable a plight as Ellis. Both men barricade the doors of the mansion. Betty, unable to gain access into the locked rooms, hurries to the city, notifies the police and goes to the home of her school chum, Claire Parr, to spend the night. During the night she is astounded to see Claire's father leave the house with a crook, Hart, both with masks. Hurriedly she seeks aid from the police and follows the men. The police arrive at Lone Willows to find the mansion a mass of flames. Inside the house a desperate battle is in progress between Ellis and Briggs and Parr and Hart. The two haunted men, having discovered Hart and Parr entering the mansion through a secret passage, believe they at last have the opportunity to kill their mysterious enemies. The police force their way into the house. Ellis and Briggs are rescued but the two crooks perish in the fire. Later Ellis learns the truth, that Parr had employed Hart, a crook, to "haunt" the mansion so that Ellis would believe Gray was carrying out his threat to kill him and reveal himself as Betty's real father. In this way he hoped to force Ellis to vacate the estate. In reality Gray died after being shot by Ellis years before. The entire affair is kept secret from Betty, and Ellis, now free for the first time from his hallucination, prepares to celebrate the wedding of Briggs and Betty.