Tarling gave one glance before he turned to the girl, who was endeavouring to push past him, and catching her by the arm gently thrust her back into the passage.

"What is wrong? What is wrong?" she asked in a terrified whisper. "Oh, let me go to mother."

She struggled to escape from his grip, but he held her firmly.

"You must be brave, for your own sake--for everybody's sake," he entreated her.

Still holding her arm, he forced her to the door of the second inner room. His hand felt for the electric switch and found it.

He was in what appeared to be a spare bedroom, plainly furnished, and from this a door led, apparently into the main building.

"Where does that door lead?" he asked, but she did not appear to hear him.

"Mother, mother!" she was moaning, "what has happened to my mother?"

"Where does that door lead?" he asked again, and for answer she slipped her trembling hand into her pocket and produced a key.

He opened the door and found himself in a rectangular gallery overlooking the hall.

She slipped past him, but he caught her and pushed her back.

"I tell you, you must be calm, Odette," he said firmly, "you must not give way. Everything depends upon your courage. Where are the servants?"

Then, unexpectedly, she broke away from him and raced back through the door into the wing they had left. He followed in swift pursuit.

"For God's sake, Odette, don't, don't," he cried, as she flung herself against the door and burst into her mother's room.

One glance she gave, then she fell on the floor by the side of her dead mother, and flinging her arms about the form kissed the cold lips.

Tarling pulled her gently away, and half-carried, half-supported her back to the gallery. A dishevelled man in shirt and trousers whom Tarling thought might be the butler was hurrying along the corridor.

"Arouse any women who are in the house," said Tarling in a low voice. "Mrs. Rider has been murdered."

"Murdered, sir!" said the startled man. "You don't mean that?"

"Quick," said Tarling sharply, "Miss Rider has fainted again."

They carried her into the drawing-room and laid her on the couch, and Tarling did not leave her until he had seen her in the hands of two women servants.

He went back with the butler to the room where the body lay. He turned on all the lights and made a careful scrutiny of the room. The window leading on to the glass-covered balcony where he had been concealed a few hours before, was latched, locked and bolted.

The curtains, which had been drawn, presumably by Milburgh when he came for the wallet, were undisturbed. From the position in which the dead woman lay and the calm on her face he thought death must have come instantly and unexpectedly. Probably the murderer stole behind her whilst she was standing at the foot of the sofa which he had partly seen through the window. It was likely that, to beguile the time of waiting for her daughter's return, she had taken a book from a little cabinet immediately behind the door, and support for this theory came in the shape of a book which had evidently fallen out of her hand between the position in which she was found and the book-case.

Together the two men lifted the body on to the sofa.

"You had better go down into the town and inform the police," said Tarling. "Is there a telephone here?"

"Yes, sir," replied the butler.

"Good, that will save you a journey," said the detective.

He notified the local police officials and then got on to Scotland Yard and sent a messenger to arouse Whiteside. The faint pallor of dawn was in the sky when he looked out of the window, but the pale light merely served to emphasise the pitch darkness of the world.

He examined the knife, which had the appearance of being a very ordinary butcher's knife. There were some faint initials burnt upon the hilt, but these had been so worn by constant handling that there was only the faintest trace of what they had originally been. He could see an "M" and two other letters that looked l............