"I beg of you not to say it!" Mrs. Rath started from her seat, and looked wildly around as though seeking some avenue of escape from a threatened disaster.

"Is it necessary to go into this, Merrington?" asked Captain Stanhill in his mild tones, glancing from the excited woman to his colleague with the troubled consciousness that he was assisting in a scene which was distasteful to him.

"Of course it is necessary if we want to get at the truth of this case," retorted Merrington. "You needn't be concerned on Mrs. Rath's account," he went on, with a kind of savage, disdainful irony. "A woman who has been tried as an accessory to murder is not likely to be squeamish. Her name is not Rath. It is Theberton—Mary Theberton. She and her husband were tried at Old Bailey fifteen years ago for the murder of a man named Bridges. The trial made a great stir at the time. It was known as 'The Death Signal Case'."

Caldew looked at the housekeeper with a new interest. He readily recalled the notorious case mentioned by Merrington. Theberton was an Essex miller, who, having discovered that his young wife was in the habit of signalling his absence to Bridges by means of a candle placed in her window, had compelled her to entice him to the cottage by the signal, and was then supposed to have murdered him by throwing him into the mill dam. But though Bridges was seen entering the cottage and was not seen afterwards, the charge of murder failed because the detectives were unable to find his body. Theberton protested his innocence; Mary Theberton said her husband locked her in her room before admitting Bridges, and she knew nothing of what took place between the two men.

There was much popular sympathy with her during the trial as the belief gained ground that the relations between her and Bridges were innocent, though indiscreet; the outcome of a craving for sympathy which had led an unhappy young wife to confide her troubles to a former schoolfellow. She was the daughter of an architect, and had been reared in refinement and educated well, but she had been disowned by her father for marrying beneath her. Her husband ill-used her, and her story was that she had sought the assistance of an old schoolfellow in order to go to London to earn a living for herself and her little daughter. When the trial was over Theberton emigrated, and his wife disappeared, although there was some talk of putting on foot a public subscription for her. This was the end of "The Death Signal Case," for the mystery of the disappearance of Bridges was never solved.

Caldew wondered by what strange turn of Fortune's wheel the woman before him had come to be housekeeper at the moat-house. It was certain that Miss Heredith knew nothing of the black page in her past, because Miss Heredith, in spite of her kind heart and rigid church principles, was the last person to appoint anybody with a tainted name to a position of trust in her household. She was too proud of the family name to do such a thing. The fact that the housekeeper had held the post so long without discovery was proof of the ease with which identity could be safely concealed from everything except chance. Although her nervous demeanour suggested that she had been walking on a razor edge of perpetual suspense in her quiet haven, ever dreading detection, it seemed to Caldew that she might have gone undiscovered to her grave but for a trick of Fate in selecting Superintendent Merrington to investigate the moat-house murder. Fate, after its cruel fashion, had left her on her razor edge for quite a long while before toppling her over, and Caldew reflected that he had been made the instrument of her fall.

But what lay beyond the exposure of the housekeeper's identity? Why had she deceived Merrington about her daughter's presence in the house? Was it only the fear that Merrington would recognize her in her early likeness to her daughter, or were her falsehoods intended to deceive the detectives about Hazel's movements at the time of the murder? What would the girl say? The situation was full of strange possibilities.

While these reflections were passing through Caldew's head there was silence in the room, broken only by the clock on the mantelpiece ticking loudly, with pert indifference to human affairs. Merrington, after dragging the hidden and forgotten tragedy to light, remained quiet, watchfully noting the effect on mother and daughter. The mother stood without a word or gesture, her hand stiffened in arrested protest, like a woman frozen into silence. The girl's look was directed towards her mother with the fixity of gaze of a sleeper awakened in the horror of a bad dream. At least in their stillness they were both in accord. Then Hazel glanced wonderingly at the faces of the others in the room, with the fatigued indifference of a returning consciousness seeking to regain its bearings. This phase passed, and in the sudden wild burst of tears which followed was the belated realization of the meaning of her mother's exposure; the shame, the agony, the disgrace which it implied. With a quick movement she rose from her seat, walked across to her mother, and caught hold of her hand.

"Mother!" she said.

But her mother turned away from her, and, sinking in her chair, covered her face in her hands with a shamed gesture, like a woman cast forth naked in the light of day.