"_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, ............