"May I keep this telegram?" asked Tarling.

The woman nodded. He saw that she was nervous, ill at ease and worried.

"I can't quite understand why Odette should not come," she said. "Is there any particular reason?"

"That I can't say," said Tarling. "But please don't let it worry you, Mrs. Rider. She probably changed her mind at the last moment and is staying with friends in town."

"Then you haven't seen her?" asked Mrs. Rider anxiously.

"I haven't seen her for several days."

"Is anything wrong?" Her voice shook for a second, but she recovered herself. "You see," she made an attempt to smile. "I have been in the house for two or three days, and I have seen neither Odette nor — nor anybody else," she added quickly.

Who was she expecting to see, wondered Tarling, and why did she check herself? Was it possible that she had not heard of the murder? He determined to test her.

"Your daughter is probably detained in town owing to Mr. Lyne's death," he said, watching her closely.

She started and went white.

"Mr. Lyne's death?" she stammered. "Has he died? That young man?"

"He was murdered in Hyde Park yesterday morning," said Tarling, and she staggered back and collapsed into a chair.

"Murdered! Murdered!" she whispered. "Oh, God! Not that, not that!"

Her face was ashen white, and she was shaking in every limb, this stately woman who had walked so serenely into the drawing-room a few minutes before.

Presently she covered her face with her hands and began to weep softly and Tarling waited.

"Did you know Mr. Lyne?" he asked after a while.

She shook her head.

"Have you heard any stories about Mr. Lyne?"

She looked up.

"None," she said listlessly, "except that he was — not a very nice man."

"Forgive me asking you, but are you very much interested — " He hesitated, and she lifted her head.

He did not know how to put this question into words. It puzzled him that the daughter of this woman, who was evidently well off, should be engaged in a more or less humble capacity in Lyne's Store. He wanted to know whether she knew that the girl had been dismissed, and whether that made much difference to her. Then again, his conversation with Odette Rider had not led him to the conclusion that she could afford to throw up her work. She spoke of finding another job, and that did not sound as though her mother was in a good position.

"Is there any necessity for your daughter working for a living?" he asked bluntly, and she dropped her eyes.

"It is her wish," she said in a low voice. "She does not get on with people about here," she added hastily.

There was a brief silence, then he rose and offered his hand.

"I do hope I haven't worried you with my questions," he said, "and I daresay you wonder why I have come. I will tell you candidly that I am engaged in investigating this murder, and I was hoping to hear that your daughter, in common with the other people who were brought into contact with Mr. Lyne, might give me some thread of a clue which would lead to more important things."

"A detective?" she asked, and he could have sworn there was horror in her eyes.

"A sort of detective," he laughed, "but not a formidable one, I hope, Mrs. Rider."

She saw him to the door, and watched him as he disappeared down the drive; then walked slowly back to the room and stood against the marble mantelpiece, her head upon her arms, weeping softly.

Jack Tarling left Hertford more confused than ever. He had instructed the fly driver to wait for him at the gates, and this worthy he proceeded to pump.

Mrs. Rider had been living in Hertford for four years, and was greatly respected. Did the cabman know the daughter? Oh yes, he had seen the young lady once or twice, but "She don't come very often," he explained. "By all accounts she doesn't get on with her father."

"Her father? I did not know she had a father," said Tarling in surprise.

Yes, there was a father. He was an infrequent visitor, and usually came up from London by the late train and was driven in his own brougham to the house. He had not seen him — indeed, very few people had, but by all accounts he was a very nice man, and well-connected in the City.

Tarling had telegraphed to the assistant who had been placed at his disposal by Scotland Yard, and Detective-Inspector Whiteside was waiting for him at the station.

"Any fresh news?" asked Tarling.

"Yes, sir, there's rather an important clue come to light," said Whiteside. "I've got the car here, sir, and we might discuss it on the way back to the Yard."

"What is it?" asked Tarling.

"We got it from Mr. Lyne's manservant," said the inspector. "It appears that the butler had been going through Mr. Lyne's things, acting on instructions from headquarters, and in a corner of his writing-desk a telegram was discovered. I'll show it you when I get to the Yard. It has a very important bearing upon the case, and I think may lead us to the murderer."

On the word "telegram" Tarling felt mechanically in his pockets for the wire which Mrs. Rider had given him from her daughter. Now he took it out and read it again. It had been handed in at the General Post Office at nine o'clock exactly.

"That's extraordinary, sir," Detective-Inspector Whiteside, sitting by his side, had overlooked the wire.

"What is extraordinary?" asked Tarling with an air of surprise.

"I happened to see the signature to that wire — 'Odette,' isn't it?" said the Scotland Yard man.

"Yes," nodded Tarling. "Why? What is there extraordinary in that?"

"Well, sir," said Whiteside, "it's something of a coincidence that the telegram which was found in Mr. Lyne's desk, and making an appointment with him at a certain flat in the Edgware Road, was also signed 'Odette,' and," he bent forward, looking at the wire still in the astonished Tarling's hand, "and," he said in triumph, "it was handed in exactly at the same time as that!"

An examination of the telegram at Scotland Yard left no doubt in the detective's mind that Whiteside had spoken nothing but the truth. An urgent message was despatched to the General Post Office, and in two hours the original telegrams were before him. They were both written in the same hand. The first to her mother, saying that she could not come; the second to Lyne, running:

"Will you see me at my flat to-night at eleven o'clock?

Odette Rider."

Tarling's heart sank within him. This amazing news was stunning. It was impossible, impossible, he told himself again and again, that this girl could have killed Lyne. Suppose she had? Where had they met? Had they gone driving together, and had she shot him in making the circuit of the Park? But why should he be wearing list slippers? Why should his coat be off, and why should the night-dress be bound round and round his body?

He thought the matter out, but the more he thought the more puzzled he became. It was a very depressed man who interviewed an authority that night and secured from him a search warrant.

Armed with this and accompanied by Whiteside he made his way to the flat in Edgware Road, and, showing his authority, secured a pass-key from the hall porter, who was also the caretaker of the building. Tarling remembered the last time he had gone to the flat, and it was with a feeling of intense pity for the girl that he turned the key in the lock and stepped into the little hall, reaching out his hand and switching on the light as he did so.

There was nothing in the hall to suggest anything unusual. There was just that close and musty smell which is peculiar to all buildings which have been shut up, even for a few days.

But there was something else.

Tarling sniffed and Whiteside sniffed. A dull, "burnt" smell, some pungent, "scorched" odour, which he recognised as the stale stench of exploded cordite. He went into the tiny dining-room; everything was neat, nothing displaced.

"That's curious," said Whiteside, pointing to the sideboard, and Tarling saw a deep glass vase half filled with daffodils. Two or three blossoms had either fallen or had been pulled out, and were lying, shrivelled and dead, on the polished surface of the sideboard.

"Humph!" said Tarling. "I don't like this very much."

He turned and walked back into the hall and opened another door, which stood ajar. Again he turned on the light. He was in the girl's bedroom. He stopped dead, and slowly examined the room. But for the disordered appearance of the chest of drawers, there was nothing unusual in the appearance of the room. At the open doors of the bureau a little heap of female attire had been thrown pell-mell upon the floor. All these were eloquent of hasty action. Still more was a small suit-case, half packed, an the bed, also left in a great hurry.

Tarling stepped into the room, and if he had been half blind he could not have missed the last and most damning evidence of all. The carpet was of a biscuit colour and covered the room flush to the wainscot. Opposite the fireplace was a big, dark red, irregular stain.

Tarling's face grew tense.

"This is where Lyne was shot," he said.

"And look there!" said Whiteside excitedly, pointing to the chest of drawers.

Tarling stepped quickly across the room and pulled out a garment which hung over the edge of the drawer. It was a night-dress — a silk night-dress with two little sprays of forget-me-nots embroidered on the sleeves. It was the companion to that which had been found about Lyne's body. And there was something more. The removal of the garment from the drawer disclosed a mark on the white enamel of the bureau. It was a bloody thumb print!

The detective looked round at his assistant, and the expression of his face was set in its hardest mask.

"Whiteside," he said quietly, "swear out a warrant for the arrest of Odette Rider on a charge of wilful murder. Telegraph all stations to detain this girl, and let me know the result."

Without another word he turned from the room and walked back to his lodgings.