He nodded.  Evidently it had attracted his attention, too.

“What makes it?” I pursued.

“Well, you know radium rays will make a diamond fluoresce in the dark.”

“Yes,” I objected, “but how about those in the comb?”

“Paste, probably,” he answered tersely, as we heard her foot on the landing.  “The rays won’t affect paste.”

It was indeed a shame to take advantage of Miss Wallace’s loyalty to Denison, but she was so game about it that I knew only the utmost necessity on Kennedy’s part would have prompted him to do it.  She had a key to the office so that it was not necessary to wait for Denison, if indeed we could have found him.

Together she and Kennedy went over the records.  It seemed that there were in the safe twenty-five platinum tubes of one hundred milligrams each, and that there had been twelve of the same amount at Pittsburgh.  Little as it seemed in weight it represented a fabulous fortune.

“You have not the combination?” inquired Kennedy.

“No.  Only Mr. Denison has that.  What are you going to do to protect the safe to-night?” she asked.

“Nothing especially,” evaded Kennedy.

“Nothing?” she repeated in amazement.

“I have another plan,” he said, watching her intently.  “Miss Wallace, it was too much to ask you to come down here.  You are ill.”

She was indeed quite pale, as if the excitement had been an overexertion.

“No, indeed,” she persisted.  Then, feeling her own weakness, she moved toward the door of Denison’s office where there was a leather couch.  “Let me rest here a moment.  I do feel queer.  I—­”

She would have fallen if he had not sprung forward and caught her as she sank to the floor, overcome by the exertion.

Together we carried her in to the couch, and as we did so the comb from her hair clattered to the floor.

Craig threw open the window, and bathed her face with water until there was a faint flutter of the eyelids.

“Walter,” he said, as she began to revive, “I leave her to you.  Keep her quiet for a few moments.  She has unintentionally given me just the opportunity I want.”

While she was yet hovering between consciousness and unconsciousness on the couch, he had unwrapped the package which he had brought with him.  For a moment he held the comb which she had dropped near the radioscope.  With a low exclamation of surprise he shoved it into his pocket.

Then from the package he drew a heavy piece of apparatus which looked as if it might be the motor part of an electric fan, only in place of the fan he fitted a long, slim, vicious-looking steel bit.  A flexible wire attached the thing to the electric light circuit and I knew that it was an electric drill.  With his coat off he tugged at the little radium safe until he had moved it out, then dropped on his knees behind it and switched the current on in the electric drill.