gh with no hope of finding anything. But a surprising
and ominous discovery rewarded him at once. In and around the key-hole,
sticking to it, were some minute fragments of wax.

"By Jove, I have it!" cried Jack. "Here is the clew! Look, Alphonse! The
scoundrel, whoever he was, took an impression in wax on his first visit.
He had a key made from it, came back later at night, and stole the
picture. It was a cunning piece of work."

"Monsieur is right," said Alphonse. "A thief has robbed him. You suspect
nobody?"

"Not a soul," replied Jack.

Though the shreds of wax showed how the studio had been entered, he was
no nearer the solution of the mystery than before. He excepted the few
trustworthy friends--only three or four--who knew that he had the
duplicate Rembrandt.

"And even in Paris there were not many who knew that I painted the
thing," he thought. "I painted it at the Hotel Netherlands, and when Von
Whele went home and left it on my hands, I locked the canvas up in an
old chest. No, I can't suspect any of my friends, past or present. But
then who--By Jove! I have overlooked one point! The man who stole the
picture knew just where it was kept, and he went straight to it.
Otherwise he would have rummaged the studio, and disarranged things
badly before he found what he wanted."

A light flashed on Jack--a light of inspiration, of certainty and
conviction. He remembered the visit of M. Felix Marchand, that he had
commented on the painting, and had seen it restored to its place in the
portfolio. Beyond doubt the mysterious Frenchman was the thief. Armed
with his craftily-won knowledge, provided with a duplicate key to the
studio, he had easily and safely accomplished his purpose. At what hour,
and on what night, it was impossible to say. Probably a day or two after
his first visit in the guise of a buyer.

"Monsieur must not take his loss too much to heart," said Alphonse, with
well-meant sympathy. "If he informs the police--"

"I prefer to have nothing to do with the police, thank you. You may go,
Alphonse. I shall dine in town, as usual."

When Alphonse had departed, Jack threw a sheet over the canvas on his
easel, put on a smoking jacket, lighted his pipe, and stretched himself
in an easy chair, to think about the startling discovery he had made.

The mystery presented many difficult points for his consideration. The
rogue's sole aim was to get that particular painting, and he had taken
nothing else, thoug