I will have nothing more to do with
your thousand guineas,--that I will leave this house?"

"Then we come to close quarters," the Prince answered, "and you force me
to tell you in plain words that, until I am ready for you to leave
it, you are as much a prisoner in this room as though the keys of the
strongest fortress in Europe were turned upon you. I have told you this
before. I thought that we perfectly understood one another."

"I did not understand," the doctor protested. "I knew that there was
trouble, but I did not know that it was this!"

"The fact of your knowing or not knowing makes no difference," the
Prince answered. "You are no longer a free agent. The only question for
you to decide is whether you remain here willingly or whether you will
force me to remind you of our bargain."

The doctor was sitting down again now. All the time he watched the
Prince with a gleam in his eyes, partly of horror, partly of fear. He no
longer doubted but that he was in the presence of a criminal.

"I am sorry," the Prince continued, "that you have allowed this little
matter to disturb you. I thought that we had arranged it all at our last
interview. If you did not surmise my reasons for keeping you here, then
I am afraid I gave you credit for more intelligence than you possess.
You will excuse me now, I am sure," he added, rising. "I have some
letters to send off before I change. By the bye, do you care to give me
your parole? It might, perhaps, lessen the inconvenience to which you
are unfortunately subject."

The doctor shook his head.

"No," he said, "I will not give my parole!"

Late that night, he tried the handle of his door and found it open. The
corridor outside was in thick darkness. He felt his way along by the
wall. Suddenly, from behind, a pair of large soft hands gripped him by
the throat. Slowly he was drawn back--almost strangled.

"Let me go!" he called out, struggling in vain to find a body upon which
he could gain a grip.

The grasp only tightened.

"Back to your rooms!" came a whisper through the darkness.

The doctor returned. When he staggered into his sitting room, he
turned up the electric light. There were red marks upon his throat and
perspiration upon his forehead. He opened the door once more and looked
out upon the landing, striking a match and holding it over his head.
There was no one in sight, yet all the time he had the uncomfortable
feeling that he was being watched. For the fir