old him about the pearl cuff-link.
He was intensely interested.

"Will you give me the link," he said, when I finished, "or, at least,
let me see it? I consider it a most important clue."

"Won't the description do?"

"Not as well as the original."

"Well, I'm very sorry," I said, as calmly as I could, "I--the thing is
lost. It--it must have fallen out of a box on my dressing-table."

Whatever he thought of my explanation, and I knew he doubted it, he
made no sign. He asked me to describe the link accurately, and I did
so, while he glanced at a list he took from his pocket.

"One set monogram cuff-links," he read, "one set plain pearl links, one
set cuff-links, woman's head set with diamonds and emeralds. There is
no mention of such a link as you describe, and yet, if your theory is
right, Mr. Armstrong must have taken back in his cuffs one complete
cuff-link, and a half, perhaps, of the other."

The idea was new to me. If it had not been the murdered man who had
entered the house that night, who had it been?

"There are a number of strange things connected with this case," the
detective went on. "Miss Gertrude Innes testified that she heard some
one fumbling with the lock, that the door opened, and that almost
immediately the shot was fired. Now, Miss Innes, here is the strange
part of that. Mr. Armstrong had no key with him. There was no key in
the lock, or on the floor. In other words, the evidence points
absolutely to this: Mr. Armstrong was admitted to the house from
within."

"It is impossible," I broke in. "Mr. Jamieson, do you know what your
words imply? Do you know that you are practically accusing Gertrude
Innes of admitting that man?"

"Not quite that," he said, with his friendly smile. "In fact, Miss
Innes, I am quite certain she did not. But as long as I learn only
parts of the truth, from both you and her, what can I do? I know you
picked up something in the flower bed: you refuse to tell me what it
was. I know Miss Gertrude went back to the billiard-room to get
something, she refuses to say what. You suspect what happened to the
cuff-link, but you won't tell me. So far, all I am sure of is this: I
do not believe Arnold Armstrong was the midnight visitor who so alarmed
you by dropping--shall we say, a golf-stick? And I believe that when
he did come he was admitted by some one in the house. Who knows--it
may have been--Liddy!"

I stirred my tea angrily.

"I have always h