“Very well,” commented Mr. Grimm.  “Let it rest as it is.  Meanwhile you may reassure madame.  Point out to her that if Monsieur Boissegur signed the letters Tuesday night he was, at least, alive; and if he came or sent for the cigarettes Wednesday night, he was still alive.  I shall call at the embassy this afternoon.  No, it isn’t advisable to go with you now.  Give me your latch-key, please.”

Monsieur Rigolot produced the key and passed it over without a word.

“And one other thing,” Mr. Grimm continued, “please collect all the revolvers that may be in the house and take charge of them yourself.  If any one, by chance, heard a burglar prowling around there to-night he might shoot, and in that event either kill Monsieur Boissegur or—­or me!”

When the secretary had gone Mr. Campbell idly drummed on his desk as he studied the face of his subordinate.

“So much!” he commented finally.

“It’s Miss Thorne again,” said the young man as if answering a question.

“Perhaps these reports I have received to-day from the Latin capitals may aid you in dispelling that mystery,” Campbell suggested, and Mr. Grimm turned to them eagerly.  “Meanwhile our royal visitor, Prince Benedetto d’Abruzzi, remains unknown?”

The young man’s teeth closed with a snap.

“It’s only a question of time, Chief,” he said abruptly.  “I’ll find him—­I’ll find him!”

And he sat down to read the reports.

XIII

A CONFERENCE IN THE DARK

The white rays of a distant arc light filtered through the half-drawn velvet hangings and laid a faintly illumined path across the ambassador’s desk; the heavy leather chairs were mere impalpable splotches in the shadows; the cut-glass knobs of a mahogany cabinet caught the glint of light and reflected it dimly.  Outside was the vague, indefinable night drone of a city asleep, unbroken by any sound that was distinguishable, until finally there came the distant boom of a clock.  It struck twice.

Seated on a couch in one corner of the ambassador’s office was Mr. Grimm.  He was leaning against the high arm of leather, with his feet on the seat, thoughtfully nursing his knees.  If his attitude indicated anything except sheer comfort, it was that he was listening.  He had been there for two hours, wide-awake, and absolutely motionless.  Five, ten, fifteen minutes more passed, and then Mr. Grimm heard the grind and whir of an automobile a block or so away, coming toward the embassy.  Now it was in front.

“Honk!  Hon-on-onk!” it called plaintively.  “Hon-on-onk!  Honk!”

The signal!  At last!  The automobile went rushing on, full tilt, while Mr. Grimm removed his feet from the seat and dropped them noiselessly to the floor.  Thus, with his hands on his knees, and listening, listening with every faculty strained, he sat motionless, peering toward the open door that led into the hall.  The car was gone now, the sound of it was swallowed up in the distance, still he sat there.  It was obviously some noise in the house for which he was waiting.