"Your pistol?" said Whiteside incredulously, "my dear good chap, you are mad! How could it be your pistol?"

"It is nevertheless my pistol," said Tarling quietly. "I recognised it the moment I saw it on your desk, and thought there must be some mistake. These furrows prove that there is no mistake at all. It has been one of my most faithful friends, and I carried it with me in China for six years."

Whiteside gasped.

"And you mean to tell me," he demanded, "that Thornton Lyne was killed with your pistol?"

Tarling nodded.

"It is an amazing but bewildering fact," he said. "That is undoubtedly my pistol, and it is the same that was found in Miss Rider's room at Carrymore Mansions, and I have not the slightest doubt in my mind that it was by a shot fired from this weapon that Thornton Lyne lost his life."

There was a long silence.

"Well, that beats me," said Whiteside, laying the weapon on the table. "At every turn some new mystery arises. This is the second jar I've had to-day."

"The second?" said Tarling. He put the question idly, for his mind was absorbed in this new and to him tremendous aspect of the crime. Thornton Lyne had been killed by his pistol! That to him was the most staggering circumstance which had been revealed since he had come into the case.

"Yes," Whiteside was saying, "it's the second setback."

With an effort Tarling brought his mind back from speculating upon the new mystery.

"Do you remember this?" said Whiteside. He opened his safe and took out a big envelope, from which he extracted a telegram.

"Yes, this is the telegram supposed to have been sent by Odette Rider, asking Mr. Lyne to call at her flat. It was found amongst the dead man's effects when the house was searched."

"To be exact," corrected Whiteside, "it was discovered by Lyne's valet—a man named Cole, who seems to be a very honest person, against whom no suspicion could be attached. I had him here this morning early to make further inquiries into Lyne's movements on the night of the murder. He's in the next room, by-the-way. I'll bring him in."

He pushed a bell and gave his instructions to the uniformed policeman who came. Presently the door opened again and the officer ushered in a respectable-looking, middle-aged man, who had "domestic service" written all over him.

"Just tell Mr. Tarling what you told me," said Whiteside.

"About that telegram, sir?" asked Cole. "Yes, I'm afraid I made a bit of a mistake there, but I got flurried with this awful business and I suppose I lost my head a bit."

"What happened?" asked Tarling.

"Well, sir, this telegram I brought up the next day to Mr. Whiteside—that is to say, the day after the murder——" Tarling nodded. "And when I brought it up I made a false statement. It's a thing I've never done before in my life, but I tell you I was scared by all these police inquiries."

"What was the false statement?" asked Tarling quickly.

"Well, sir," said the servant, twisting his hat nervously, "I said that it had been opened by Mr. Lyne. As a matter of fact, the telegram wasn't delivered until a quarter of an hour after Mr. Lyne left the place. It was I who opened it when I heard of the murder. Then, thinking that I should get into trouble for sticking my nose into police business, I told Mr. Whiteside that Mr. Lyne had opened it."

"He didn't receive the telegram?" asked Tarling.

"No, sir."

The two detectives looked at one another.

"Well, what do you make of that, Whiteside?"

"I'm blest if I know what to think of it," said Whiteside, scratching his head. "We depended upon that telegram to implicate the girl. It breaks a big link in the chain against her."

"Supposing it was not already broken," said Tarling almost aggressively.

"And it certainly removes the only possible explanation for Lyne going to the flat on the night of the murder. You're perfectly sure, Cole, that that telegram did not reach Mr. Lyne?"

"Perfectly, sir," said Cole emphatically. "I took it in myself. After Mr. Lyne drove off I went to the door of the house to get a little fresh air, and I was standing on the top step when it came up. If you notice, sir, it's marked 'received at 9.20'—that means the time it was received at the District Post Office, and that's about two miles from our place. It couldn't possibly have got to the house before Mr. Lyne left, and I was scared to death that you clever gentlemen would have seen that."

"I was so clever that I didn't see it," admitted Tarling with a smile. "Thank you, Mr. Cole, that will do."

When the man had gone, he sat down on a chair opposite Whiteside and thrust his hands into his pockets with a gesture of helplessness.

"Well, I'm baffled," he said. "Let me recite the case, Whiteside, because it's getting so complicated that I'm almost forgetting its plainest features. On the night of the fourteenth Thornton Lyne is murdered by some person or persons unknown, presumably in the flat of Odette Rider, his former cashier, residing at Carrymore Mansions. Bloodstains are found upon the floor, and there is other evidence, such as the discovery of the pistol and the spent bullet, which emphasises the accuracy of that conclusion. Nobody sees Mr. Lyne come into the flat or go out. He is found in Hyde Park the next morning without his coat or vest, a lady's silk night-dress, identified as Odette Rider's, wrapped tightly round his breast, and two of Odette Rider's handkerchiefs are found over the wound. Upon his body are a number of daffodils, and his car, containing his coat, vest and boots, is found by the side of the road a hundred yards away. Have I got it right?"

Whiteside nodded.

"Whatever else is at fault," he smiled, "your memory is unchallengeable."

"A search of the bedroom in which the crime was committed reveals a bloodstained thumb-print on the white bureau, and a suit-case, identified as Odette Rider's, half-packed upon the bed. Later, a pistol, which is mine, is found in the lady's work-basket, hidden under repairing material. The first suggestion is that Miss Rider is the murderess. That suggestion is refuted, first by the fact that she was at Ashford when the murder was committed, unconscious as a result of a railway accident; and the second point in her favour is that the telegram discovered by Lyne's valet, purporting to be signed by the girl, inviting Lyne to her flat at a certain hour, was not delivered to the murdered man."

He rose to his feet.

"Come along and see Cresswell," he said. "This case is going to drive me mad!"

Assistant Commissioner Cresswell heard the story the two men had to tell, and if he was astounded he did not betray any signs of his surprise.

"This looks like being the murder case of the century," he said. "Of course, you cannot proceed any further against Miss Rider, and you were wise not to make the arrest. However, she must be kept under observation, because apparently she knows, or think she knows, the person who did commit the murder. She must be watched day and night, and sooner or later, she will lead you to the man upon whom her suspicions rest.

"Whiteside had better see her," he said, turning to Tarling. "He may get a new angle of her view. I don't think there's much use in bringing her down here. And, by-the-way, Tarling, all the accounts of Lyne's Stores have been placed in the hands of a clever firm of chartered accountants—Dashwood and Solomon, of St. Mary Axe. If you suspect there has been any peculation on the part of Lyne's employees, and if that peculation is behind the murder, we shall probably learn something which will give you a clue."

Tarling nodded.

"How long will the examination take?" he asked.

"They think a week. The books have been taken away this morning—which reminds me that your friend, Mr. Milburgh—I think that is his name—is giving every assistance to the police to procure a faithful record of the firm's financial position."

He looked up at Tarling and scratched his nose.

"So it was committed with your pistol, Tarling?" he said with a little smile. "That sounds bad."

"It sounds mad," laughed Tarling. "I'm going straight back to discover what happened to my pistol and how it got into that room. I know that it was safe a fortnight ago because I took it to a gunsmith to be oiled."

"Where do you keep it as a rule?"

"In the cupboard with my colonial kit," said Tarling. "Nobody has access to my room except Ling Chu, who is always there when I'm out."

"Ling Chu is your Chinese servant?"

"Not exactly a servant," smiled Tarling. "He is one of the best native thief catchers I have ever met. He is a man of the greatest integrity and I would trust him with my life."

"Murdered with your pistol, eh?" asked the Commissioner.

There was a little pause and then:

"I suppose Lyne's estate will go to the Crown? He has no relations and no heir."

"You're wrong there," said Tarling quietly.

The Commissioner looked up in surprise.

"Has he an heir?" he asked.

"He has a cousin," said Tarling with a little smile, "a relationship close enough to qualify him for Lyne's millions, unfortunately."

"Why unfortunately?" asked Mr. Cresswell.

"Because I happen to be the heir," said Tarling.