Tarling, his hands thrust into his pockets, his chin dropped, his shoulders bent, slowly walked the broad pavement of the Edgware Road on his way from the girl's hotel to his flat. He dismissed with good reason the not unimportant fact that he himself was suspect. He, a comparatively unknown detective from Shanghai was by reason of his relationship to Thornton Lyne, and even more so because his own revolver had been found on the scene of the tragedy, the object of some suspicion on the part of the higher authorities who certainly would not pooh-pooh the suggestion that he was innocent of any association with the crime because he happened to be engaged in the case.

He knew that the whole complex machinery of Scotland Yard was working, and working at top speed, to implicate him in the tragedy. Silent and invisible though that work may be, it would nevertheless be sure. He smiled a little, and shrugged himself from the category of the suspected.

First and most important of the suspects was Odette Rider. That Thornton Lyne had loved her, he did not for one moment imagine. Thornton Lyne was not the kind of man who loved. Rather had he desired, and very few women had thwarted him. Odette Rider was an exception. Tarling only knew of the scene which had occurred between Lyne and the girl on the day he had been called in, but there must have been many other painful interviews, painful for the girl, humiliating for the dead millionaire.

Anyway, he thought thankfully, it would not be Odette. He had got into the habit of thinking of her as "Odette," a discovery which had amused him. He could rule her out, because obviously she could not be in two places at once. When Thornton Lyne was discovered in Hyde Park, with Odette Rider's night-dress round about his wound, the girl herself was lying in a cottage hospital at Ashford fifty miles away.

But what of Milburgh, that suave and oily man? Tarling recalled the fact that he had been sent for by his dead relative to inquire into Milburgh's mode of living and that Milburgh was under suspicion of having robbed the firm. Suppose Milburgh had committed the crime? Suppose, to hide his defalcations, he had shot his employer dead? There was a flaw in this reasoning because the death of Thornton Lyne would be more likely to precipitate the discovery of the manager's embezzlements—there would be an examination of accounts and everything would come out. Milburgh himself was not unmindful of this argument in his favour, as was to be revealed.

As against this, Tarling thought, it was notorious that criminals did foolish things. They took little or no account of the immediate consequences of their act, and a man like Milburgh, in his desperation, might in his very frenzy overlook the possibility of his crime coming to light through the very deed he had committed to cover himself up.

He had reached the bottom of Edgware Road and was turning the corner of the street, looking across to the Marble Arch, when he heard a voice hail him and turning, saw a cab breaking violently to the edge of the pavement.

It was Inspector Whiteside who jumped out.

"I was just coming to see you," he said. "I thought your interview with the young lady would be longer. Just wait a moment, till I've paid the cabman—by-the-way, I saw your Chink servant and gather you sent him to the Yard on a spoof errand."

When he returned, he met Tarling's eye and grinned sympathetically.

"I know what's in your mind," he said frankly, "but really the Chief thinks it no more than an extraordinary coincidence. I suppose you made inquiries about your revolver?"

Tarling nodded.

"And can you discover how it came to be in the possession of——" he paused, "the murderer of Thornton Lyne?"

"I have a theory, half-formed, it is true, but still a theory," said Tarling. "In fact, it's hardly so much a theory as an hypothesis."

Whiteside grinned again.

"This hair-splitting in the matter of logical terms never did mean much in my young life," he said, "but I take it you have a hunch."

Without any more to-do, Tarling told the other of the discovery he had made in Ling Chu's box, the press cuttings, descriptive of the late Mr. Lyne's conduct in Shanghai and its tragic sequel.

Whiteside listened in silence.

"There may be something on that side," he said at last when Tarling had finished. "I've heard about your Ling Chu. He's a pretty good policeman, isn't he?"

"The best in China," said Tarling promptly, "but I'm not going to pretend that I understand his mind. These are the facts. The revolver, or rather the pistol, was in my cupboard and the only person who could get at it was Ling Chu. There is the second and more important fact imputing motive, that Ling Chu had every reason to hate Thornton Lyne, the man who had indirectly been responsible for his sister's death. I have been thinking the matter over and I now recall that Ling Chu was unusually silent after he had seen Lyne. He has admitted to me that he has been to Lyne's Store and in fact has been pursuing inquiries there. We happened to be discussing the possibility of Miss Rider committing the murder and Ling Chu told me that Miss Rider could not drive a motor-car and when I questioned him as to how he knew this, he told me that he had made several inquiries at the Store. This I knew nothing about.

"Here is another curious fact," Tarling went on. "I have always been under the impression that Ling Chu did not speak English, except a few words of 'pigeon' that Chinamen pick up through mixing with foreign devils. Yet he pushed his inquiries at Lyne's Store amongst the employees, and it is a million to one against his finding any shop-girl who spoke Cantonese!"

"I'll put a couple of men on to watch him," said Whiteside, but Tarling shook his head.

"It would be a waste of good men," he said, "because Ling Chu could lead them just where he wanted to. I tell you he is a better sleuth than any you have got at Scotland Yard, and he has an absolute gift for fading out of the picture under your very nose. Leave Ling Chu to me, I know the way to deal with him," he added grimly.

"The Little Daffodil!" said Whiteside thoughtfully, repeating the phrase which Tarling had quoted. "That was the Chinese girl's name, eh? By Jove! It's something more than a coincidence, don't you think, Tarling?"

"It may be or may not be," said Tarling; "there is no such word as daffodil in Chinese. In fact, I am not so certain that the daffodil is a native of China at all, though China's a mighty big place. Strictly speaking the girl was called 'The Little Narcissus,' but as you say, it may be something more than a coincidence that the man who insulted her, is murdered whilst her brother is in London."

They had crossed the broad roadway as they were speaking and had passed into Hyde Park. Tarling thought whimsically that this open space exercised the same attraction on him as it did upon Mr. Milburgh.

"What were you going to see me about?" he asked suddenly, remembering that Whiteside had been on his way to the hotel when they had met.

"I wanted to give you the last report about Milburgh."

Milburgh again! All conversation, all thought, all clues led to that mystery man. But what Whiteside had to tell was not especially thrilling. Milburgh had been shadowed day and night, and the record of his doings was a very prosaic one.

But it is out of prosaic happenings that big clues are born.

"I don't know how Milburgh expects the inquiry into Lyne's accounts will go," said Whiteside, "but he is evidently connected, or expects to be connected, with some other business."

"What makes you say that?" asked Tarling.

"Well," replied Whiteside, "he has been buying ledgers," and Tarling laughed.

"That doesn't seem to be a very offensive proceeding," he said good-humouredly. "What sort of ledgers?"

"Those heavy things which are used in big offices. You know, the sort of thing that it takes one man all his time to lift. He bought three at Roebuck's, in City Road, and took them to his house by taxi. Now my theory," said Whiteside earnestly, "is that this fellow is no ordinary criminal, if he is a criminal at all. It may be that he has been keeping a duplicate set of books."

"That is unlikely," interrupted Tarling, "and I say this with due respect for your judgment, Whiteside. It would want to be something more than an ordinary criminal to carry all the details of Lyne's mammoth business in his head, and it is more than possible that your first theory was right, namely, that he contemplates either going with another firm, or starting a new business of his own. The second supposition is more likely. Anyway, it is no crime to own a ledger, or even three. By-the-way, when did he buy these books?"

"Yesterday," said Whiteside, "early in the morning, before Lyne's opened. How did your interview with Miss Rider go off?"

Tarling shrugged his shoulders. He felt a strange reluctance to discuss the girl with the police officer, and realised just how big a fool he was in allowing her sweetness to drug him.

"I am convinced that, whoever she may suspect, she knows nothing of the murder," he said shortly.

"Then she does suspect somebody?"

Tarling nodded.

"Who?"

Again Tarling hesitated.

"I think she suspects Milburgh," he said.

He put his hand in the inside of his jacket and took out a pocket case, opened it, and drew forth the two cards bearing the finger impressions he had taken of Odette Rider. It required more than an ordinary effort of will to do this, though he would have found it difficult to explain just what tricks his emotions were playing.

"Here are the impressions you wanted," he said. "Will you take them?"

Whiteside took the cards with a nod and examined the inky smudges, and all the time Tarling's heart stood still, for Inspector Whiteside was the recognised authority of the Police Intelligence Department on finger prints and their characteristics.

The survey was a long one.

Tarling remembered the scene for years afterwards; the sunlit path, the straggling idlers, the carriages pursuing their leisurely way along the walks, and the stiff military figure of Whiteside standing almost to attention, his keen eyes peering down at the little cards which he held in the finger-tips of both hands. Then:

"Interesting," he said. "You notice that the two figures are almost the same—which is rather extraordinary. Very interesting."

"Well?" asked Tarling impatiently, almost savagely.

"Interesting," said Whiteside again, "but none of these correspond to the thumb prints on the bureau."

"Thank God for that!" said Tarling fervently "Thank God for that!"