"Maybe we could pull this last job," Hoges agreed. "Does he know much about painting?"
"Very little. We ought to nip him for three thousand at least."
Hoges glanced at his watch.
"If your customer is coming at one-thirty we'd better get the stage set."
"All right," Cron nodded. "Let's clean up the joint."
Uncovering the genuine Rembrandt, he took one of the copies, and deftly inserted it in the picture frame behind the original painting, but in such a manner that only the back of the canvas was visible. When the frame was replaced only a person with keen eyesight could detect the trickery.
"We'll pull the usual gag about identifying the picture with a signature or a symbol," Cron muttered. "That always goes big."
By this time Penny had seen enough to understand how Mrs. Dillon and other gullible customers had been duped. They had been shown the original stolen Rembrandt, but when invited to place an identifying mark on the back of the canvas to insure that they received the same picture, actually signed the fake copy. It was then a simple matter to remove the two paintings from the frame and send the customer the worthless one which bore his mark.
"Cron and his confederates have worked a fairly safe racket too," Penny thought. "Even if a customer learns he has been cheated, he's afraid to go to the police for fear he'll expose himself as a person willing to buy stolen property!"
She was not greatly surprised to learn that Cron was a party to the dishonest scheme, notwithstanding that Mrs. Dillon had denied the art critic was the mysterious agent who had visited her. Now Penny knew that the woman had not spoken the truth. Doubtlessly, she had feared to accuse Cron, lest he in turn expose her to the police.