hat the door had been closed while he had
been busy with his investigations.

He sprang against it.

The door yielded a little, and yet he could not open it.

Some person stronger than he seemed to be holding it on the other side.

He drew back for a spring. That door would have gone to splinters if it
had stood in his way again.

Instead, it swung open the instant he touched it, and the force of his
lunge took him nearly to the middle of the room.

In an instant he was on guard, but he saw no one.

The room was quiet, and it was empty.

The door into the hall was locked as he had left it.

All was the same, except that on the dressing-table was the cushion
bearing two diamond pins instead of three.

The robbery had been done, as one might say, under the nose of the
greatest detective in the world.

"Well, this takes my breath away," said Nick to himself. "It's the
nerviest challenge that ever was sprung on me."

CHAPTER III.

HOW NICK FOUND THE JEWELS.

It certainly looked like sheer recklessness for this thief, whoever he
might be, to play his game on Nick almost at the very moment when the
great detective appeared upon the scene.

Shrewd as Nick was, he had not expected this. His first thought, as the
reader knows, was that it was a bold challenge, the defiance of a nervy
criminal who thought himself absolutely safe from detection.

But a moment's reflection made this seem less probable.

Was it not more natural to suppose that this event proved that the
detective was unknown to the thief?

Such being the case, Colonel Richmond, his nephew and Mrs. Pond were
acquitted at the start.

It may seem ridiculous to suspect them, in any case, but so strange was
the nature of this affair that Nick gave nobody the credit of certain
innocence.

Colonel Richmond was certainly very nearly crazy on one point. He might
be so much of a lunatic as to commit these robberies from simple
delusion. Or he might wish to prove to his daughter that the diamonds
were not rightfully hers.

Mrs. Pond might be pawning them for small extravagances which she was
afraid to have known.

As to Horace Richmond, there was no motive which seemed plausible. The
value of the articles taken was so small as to make the game not worth
while for a man in his position.

And it was perfectly certain that no professional thief or dishonest
servant was doing the work.

If such a person had been in the game, he would not hav