When I came out there were two. What happened to the third whilst I was locked in the room?"
Doctor van Heerden shook his head pityingly.
"I am afraid, I am very much afraid, that you are not right in your head," he said, and nodded toward the place where the cases stood.
Beale followed the direction of his head and gasped, for there were three cases.
"I admit that I deceived you when I said they contained specimens. As a matter of fact, they are empty," said the doctor. "If you like to inspect them, you can. You may find some—clue!"
Beale wanted no invitation. He walked to the cases one by one and sounded them. Their lids were screwed on but the screws were dummies. He found in the side of each a minute hole under the cover of the lid and, taking out his knife, he pressed in the bodkin with which the knife was equipped and with a click the lid flew open. The box was empty. The second one answered the same test and was also empty. The third gave no better result. He flashed his lamp on the bottom of the box, but there was no trace of footmarks.
"Are you satisfied?" asked the doctor.
"Far from satisfied," said Beale, and with no other word he walked out and down the stairs again.
Half-way down he saw something lying on one of the stairs and picked it up. It was a shoe, the fellow of that which he had in his pocket, and it had not been there when he came up.
*****
Oliva Cresswell had read the story of the crime in the Post Record, had folded up the paper with a little shiver and was at her tiny writing-bureau when a knock came at the door. It was Dr. van Heerden.
"Can I come in for a moment ? " he asked.
She hesitated.
"I shan't eat you," he smiled, "but I am so distressed by what has happened and I feel that an explanation is due to you."
