Felix nodded and put the crumpled-up piece of paper in his pocket.  The two men passed on.  Duson took off his hat, but his fingers were trembling.  The carriage door was opened and a tall, spare man descended.

“This is Mr. Sabin?” he remarked.

Mr. Sabin bowed.

“That is my name,” he admitted, “by which I have been generally called in this democratic country.  What is your business with me?”

“I rather guess that you’re my prisoner,” the man answered.  “If you’ll step right in here we can get away quietly.”

“The suggestion,” Mr. Sabin remarked, “sounds inviting, but I am somewhat pressed for time.  Might I inquire the nature of the charge you have against me?”

“They’ll tell you that at the office,” the man answered.  “Get in, please.”

Mr. Sabin looked around for Felix, but he had disappeared.  He took out his cigarette-case.

“You will permit me first to light a cigarette,” he remarked.

“All right!  Only look sharp.”

Mr. Sabin kept silence in the carriage.  The drive was a long one.  When they descended he looked up at Duson, who sat upon the box.

“Duson,” he said, and his voice, though low, was terrible, “I see that I can be mistaken in men.  You are a villain.”

The man sprung to his feet, hat in hand.  His face was wrung with emotion.

“Your Grace,” he said, “it is true that I betrayed you.  But I did it without reward.  I am a ruined man.  I did it because the orders which came to me were such as I dare not disobey.  Here are your keys, your Grace, and money.”

Mr. Sabin looked at him steadily.

“You, too, Duson?”

“I too, alas, your Grace!”

Mr. Sabin considered for a moment.

“Duson,” he said, “I retain you in my service.  Take my luggage on board the Campania to-morrow afternoon, and pay the bill at the hotel.  I shall join you on the boat.”

Duson was amazed.  The man who was standing by laughed.

“If you take my advice, sir,” he remarked, “you’ll order your clothes to be sent here.  I’ve a kind of fancy the Campania will sail without you to-morrow.”

“You have my orders, Duson,” Mr. Sabin said.  “You can rely upon seeing me.”

The detective led the way into the building, and opened the door leading into a large, barely furnished office.

“Chief’s gone home for the night, I guess,” he remarked.  “We can fix up a shakedown for you in one of the rooms behind.”

“I thank you,” Mr. Sabin said, sitting down in a high-backed wooden chair; “I decline to move until the charge against me is properly explained.”

“There is no one here to do it just now,” the man answered.  “Better make yourself comfortable for a bit.”

“You detain me here, then,” Mr. Sabin said, “without even a sight of your warrant or any intimation as to the charge against me?”