For a little time the intruder stood staring down at the still body, then he went to the telephone and called police headquarters.

“There has been a jail delivery at the prison,” he said in answer to the “hello” of the desk-sergeant at the other end of the wire.  “Better send some of your men up to investigate.”

“Who is that?” came the answering question.

The stranger replaced the receiver on the hook, stripped off his black mask, dropped it on the floor beside the motionless warden, and went out.  It was Mr. Grimm!

XVIII

NOTICE TO LEAVE

At fifteen minutes of midnight when Miss Thorne, followed by Signor Petrozinni, entered the sitting-room of her apartments in the hotel and turned up the light they found Mr. Grimm already there.  He rose courteously.  At sight of him Miss Thorne’s face went deathly white, and the escaped prisoner turned toward the door again.

“I would advise that you stay, your Highness,” said Mr. Grimm coldly.  Signor Petrozinni paused, amazed.  “You will merely subject yourself to the humiliation of arrest if you attempt to leave.  The house is guarded by a dozen men.”

“Your Highness?” Miss Thorne repeated blankly.  “You are assuming a great deal, aren’t you, Mr. Grimm?”

“I don’t believe,” and Mr. Grimm’s listless eyes were fixed on those of the escaped prisoner, “I don’t believe that Prince Benedetto d’Abruzzi will deny his identity?”

There was one of those long tense silences when eye challenges eye, when wit is pitted against wit, and mind is hauled around to a new, and sometimes unattractive, view of a situation.  Miss Thorne stood silent with rigid features, colorless as marble; but slowly a sneer settled about the lips of Signor Petrozinni that was, and he sat down.

[Illustration:  A long tense silence when eye challenges eye.]

“You seem to know everything, Mr. Grimm,” he taunted.

“I try to know everything, your Highness,” was the reply.  Mr. Grimm was still standing.  “I know, for instance, that one week ago the plot which had your freedom for its purpose was born; I know the contents of every letter that passed between you and Miss Thorne here, notwithstanding the invisible ink; I know that four days ago several thousand dollars was smuggled in to you concealed in a basket of fruit; I know, with that money, you bribed your way out, while Miss Thorne or one of her agents bribed the guard in front; I know that the escape was planned for to-night, and that the man who was delegated to take charge of it is now locked in my office under guard.  It may interest you to know that it was I who took his place and made the escape possible.  I know that much!”

“You—­you—!” the prince burst out suddenly. “You aided me to escape?”

Miss Thorne was staring, staring at them with her eyes widely distended, and her red lips slightly parted.