e trick was done.

"You will all be given a chance to claim the reward under the usual
conditions after the trick has been performed by Professor Strong," was
the announcement made.

As the description of the manner in which Joe and Helen did the trick is
given in all its details in the volume preceding this, suffice it here
to say that Joe got into the box, which was locked and roped, and, at
the proper time, he appeared outside.

"Is there any one who can tell how the trick was done, and so earn the
ten thousand dollar reward?" asked the manager. He had made this
announcement many times. Seldom, of late, had any one come forward. But
now, somewhat to the surprise of Joe and his friends, a man's voice
called from a location near the platform:

"I can tell how it was done!"

"Will you please come forward," invited Joe, now taking charge of the
proceedings.

A fairly well-dressed man stepped across the arena and approached the
stage. Joe and Jim Tracy and the others vitally interested looked
closely at him. He was not Bill Carfax--that was certain. And Joe did
not know the man, nor, as Jim Tracy admitted afterward, did he.

"You say you can tell how I get out of the box?" asked Joe, and the
audience listened intently.

"Yes. I know the secret."

"Are you willing to post a hundred dollars to be forfeited to the Red
Cross in case you fail?" went on the young magician.

"I am. Here is the money!" was the cool response. This quick compliance
with the terms of the offer rather staggered Joe. But he had no fear as
to the outcome.

"Very well," went on the originator of the box trick. "The ringmaster
will hold your money. If you are successful in telling how I get out of
the box the cash will be handed back to you, and you will receive, in
addition, a check for ten thousand dollars. Now then, how do I get out
of the box? Tell the audience."

There was a moment of suspense, and then the man, with an air of
confidence, stepped close to the big, heavy box and, pointing to a
certain corner, said:

"Right there is a secret panel. You slip it back and get out that way!"

The man seemed so triumphantly confident and so sure of his statement,
that several in the audience cried:

"Is that right? Is that how you do the trick? If it is pay him the ten
thousand dollars!"

Joe looked at Jim Tracy. This was the first time any one had ever come
so close to the truth. Helen, standing at one side of the stage, began
to be