Then he turned the last page. Morton had written that page only yesterday, the day he died.
"Sept. 21, 1940. Succeeded in opening the box today. As I suspected it was closed by a combination lock. Deucedly clever thing, that lock. Not like any lock in use today. Patent rights on it might provide the museum with some of the cash it so badly needs.
"To my great astonishment, and regret, when I opened the box, I found it empty."
Rocks Malone started at the words Morton had written. Penny had been reading over her shoulder. He heard her catch her breath.
EMPTY! The single word seemed to leap out at him. How on earth could Morton make a mistake like that!
There was another line of writing. "Weighed box. Find that it weighs nine pounds less than it did when I brought it here."
In the fleeting flash of a second, Rocks saw the whole picture. Or almost all of it. There were parts that needed clearing up. But he knew at last the real significance of the fact that Morton had weighed the box a second time.
"There's somebody coming!" Penny whispered.
A step had sounded on the stairs outside the room. The door opened. Sharp entered.
He had a traveling bag with him.