“Appointment?” he repeated with the rising inflection, taking the paper.

“It was delivered at my hotel half an hour ago,” she told him. “I presumed you ...”

“No,” said Staff. “Half a minute....”

He shut the door and unfolded the note. The paper and the chirography, he noticed, were identical with those of the note received by Iff from Hartford. With this settled to his satisfaction, he read the contents aloud, raising his voice a trifle for the benefit of the listener in the back room.

“‘If Miss Landis wishes to arrange for the return of the Cadogan collar, will she be kind enough to call at Mr. Staff’s rooms in Thirtieth Street at a quarter to ten tonight.

“‘N. B.—Any attempt to bring the police or private detectives or other outsiders into the negotiations will be instantly known to the writer and—there won’t be any party.’

“Unsigned,” said Staff reflectively.

“Well?” demanded Alison, seating herself.

“Curious,” remarked Staff, still thinking.

“Well?” she iterated less patiently. “Is it a practical joke?”