“So?” considered Kennedy.  “Then that would mean that they might have been taken by any one, don’t you see?  Why did he place them in the safe so soon, instead of wearing them the rest of the evening?”

“I hadn’t thought of that way of looking at it,” she admitted.  “Why, when we came home from the theater I remember it had been so warm that Mr. Mansfield’s collar was wilted and his dress shirt rumpled.  He excused himself, and when he returned he was not wearing the diamonds.  We noticed it, and Miss Hargrave expressed a wish that she might wear the big diamond at the opening night of ‘The Astor Cup.’  Mr. Mansfield promised that she might and nothing more was said about it.”

“Did you notice anything else at the dinner—­no matter how trivial?” asked Kennedy.

Helen Grey seemed to hesitate, then said, in a low voice, as though the words were wrung from her: 

“Of course, the party and the supper were given ostensibly to Miss Hargrave.  But—­lately—­I have thought he was paying quite as much attention to Mina Leitch.”

It was quite in keeping with what we knew of “Diamond Jack.”  Perhaps it was this seeming fickleness which had saved him from many entangling alliances.  Miss Grey said it in such a way that it seemed like an apology for a fault in his character which she would rather have hidden.  I could not but fancy that it mitigated somewhat the wistful envy I had noticed before when she spoke of Madeline Hargrave.

While he had been questioning her Kennedy had been examining the wall safe, particularly with reference to its accessibility from the rest of the apartment.  There appeared to be no reason why one could not have got at it from the hallway as well as from Mansfield’s room.

The safe itself seemed to yield no clue, and Kennedy was about to turn away when he happened to glance down at the dark interior of the closet floor.  He stooped down.  When he rose he had something in his hand.  It was just a little thin piece of something that glittered iridescently.

“A spangle from a sequin dress,” he muttered to himself; then, turning to Miss Grey, “Did any one wear such a dress last night?”

Helen Grey looked positively frightened.  “Miss Hargrave!” she murmured, simply.  “Oh, it cannot be—­there must be some mistake!”

Just then we heard voices in the hall.

“But, Murray, I don’t see why I can’t see him,” said one.

“What good will it do, Lewis?” returned the other, which I recognized as that of Doctor Murray.

“Fleming Lewis,” whispered Miss Grey, taking a step out into the hallway.

A moment later Doctor Murray and Lewis had joined us.

I could see that there was some feeling between the two men, though what it was about I could not say.  As Miss Grey introduced us, I glanced hastily out of the corner of my eye at Kennedy.  Involuntarily his hand which held the telltale sequin had sought his waistcoat pocket, as though to hide it.  Then I saw him check the action and deliberately examine the piece of tinsel between his thumb and forefinger.