The matron of the nursing home received Tarling. Odette, she said, had regained her normal calm, but would require a few days' rest. She suggested she should be sent to the country.

"I hope you're not going to ask her a lot of questions, Mr. Tarling," said the matron, "because she really isn't fit to stand any further strain."

"There's only one question I'm going to ask," said Tarling grimly.

He found the girl in a prettily-furnished room, and she held out her hand to him in greeting. He stooped and kissed her, and without further ado produced the shoe from his pocket.

"Odette dear," he said gently, "is this yours?"

She looked at it and nodded.

"Why yes, where did you find it?"

"Are you sure it is yours?"

"I'm perfectly certain it's mine," she smiled. "It's an old slipper I used to wear. Why do you ask?"

"Where did you see it last?"

The girl closed her eyes and shivered.

"In mother's room," she said. "Oh, mother, mother!"

She turned her head to the cushion of the chair and wept, and Tarling soothed her.

It was some time before she was calm, but then she could give no further information.

"It was a shoe that mother liked because it fitted her. We both took the same size...."

Her voice broke again and Tarling hastened to change the conversation.

More and more he was becoming converted to Ling Chu's theory. He could not apply to that theory the facts which had come into his possession. On his way back from the nursing home to police headquarters, he reviewed the Hertford crime.

Somebody had come into the house bare-footed, with bleeding feet, and, having committed the murder, had looked about for shoes. The old slippers had been the only kind which the murderer could wear, and he or she had put them on and had gone out again, after making the circuit of the house. Why had this mysterious person tried to get into the house again, and for whom or what were they searching?

If Ling Chu was correct, obviously the murderer could not be Milburgh. If he could believe the evidence of his senses, the man with the small feet had been he who had shrieked defiance in the darkness and had hurled the vitriol at his feet. He put his views before his subordinate and found Whiteside willing to agree with him.

"But it does not follow," said Whiteside, "that the bare-footed person who was apparently in Mrs. Rider's house committed the murder. Milburgh did that right enough, don't worry! There is less doubt that he committed the Daffodil Murder."

Tarling swung round in his chair; he was sitting on the opposite side of the big table that the two men used in common.

"I think I know who committed the Daffodil Murder," he said steadily. "I have been working things out, and I have a theory which you would probably describe as fantastic."

"What is it?" asked Whiteside, but the other shook his head.

He was not for the moment prepared to reveal his theory.

Whiteside leaned back in his chair and for a moment cogitated.

"The case from the very beginning is full of contradictions," he said. "Thornton Lyne was a rich man — by-the-way, you're a rich man, now, Tarling, and I must treat you with respect."

Tarling smiled.

"Go on," he said.

"He had queer tastes — a bad poet, as is evidenced by his one slim volume of verse. He was a poseur, proof of which is to be found in his patronage of Sam Stay — who, by the way, has escaped from the lunatic asylum; I suppose you know that?"

"I know that," said Tarling. "Go on."

"Lyne falls in love with a pretty girl in his employ," continued Whiteside. "Used to having his way when he lifted his finger, all women that in earth do dwell must bow their necks to the yoke. He is repulsed by the girl and in his humiliation immediately conceives for her a hatred beyond the understanding of any sane mortal."

"So far your account doesn't challenge contradiction," said Tarling with a little twinkle in his eye.

"That is item number one," continued Whiteside, ticking the item off on his fingers. "Item number two is Mr. Milburgh, an oleaginous gentleman who has been robbing the firm for years and has been living in style in the country on his ill-earned gains. From what he hears, or knows, he gathers, that the jig is up. He is in despair when he realises that Thornton Lyne is desperately in love with his step-daughter. What is more likely than that he should use his step-daughter in order to influence Thornton Lyne to take the favourable view of his delinquencies?"

"Or what is more likely," interrupted Tarling, "than that he would put the blame for the robberies upon the girl and trust to her paying a price to Thornton Lyne to escape punishment?"

"Right again. I'll accept that possibility," said Whiteside. "Milburgh's plan is to get a private interview, under exceptionally favourable circumstances, with Thornton Lyne. He wires to that gentleman to meet him at Miss Rider's flat, relying upon the magic of the name."

"And Thornton Lyne comes in list slippers," said Tarling sarcastically. "That doesn't wash, Whiteside."

"No, it doesn't," admitted the other. "But I'm getting at the broad aspects of the case. Lyne comes. He is met by Milburgh, who plays his trump card of confession and endeavours to switch the young man on to the solution which Milburgh had prepared. Lyne refuses, there is a row, and is desperation Milburgh shoots Thornton Lyne."

Tarling shook his head. He mused a while, then:

"It's queer," he said.

The door opened and a police officer came in.

"Here are the particulars you want," he said and handed Whiteside a typewritten sheet of paper.

"What is this?" said Whiteside when the man had gone. "Oh, here is our old friend, Sam Stay. A police description." He read on: "Height five foot four, sallow complexion ... wearing a grey suit and underclothing bearing the markings of the County Asylum.... Hullo!"

"What is it?" said Tarling.

"This is remarkable," said Whiteside, and read

"When the patient escaped, he had bare feet. He takes a very small size in shoes, probably four or five. A kitchen knife is missing and the patient may be armed. Boot-makers should be warned...."

"Bare feet!" Tarling rose from the table with a frown on his face. "Sam Stay hated Odette Rider."

The two men exchanged glances.

"Now, do you see who killed Mrs. Rider?" asked Tarling. "She was killed by one who saw Odette Rider go into the house, and did not see her come out; who went in after her to avenge, as he thought, his dead patron. He killed this unhappy woman — the initials on the knife, M.C.A., stand for Middlesex County Asylum, and he brought the knife with him — and discovered his mistake; then, having searched for a pair of shoes to cover his bleeding feet, and having failed to get into the house by any other way, made a circuit of the building, looking for Odette Rider and seeking an entrance at every window."

Whiteside looked at him in astonishment.

"It's a pity you've got money," he said admiringly. "When you retire from this business there'll be a great detective lost."