“Very true; we have the Clephane letter, as you style it; and we have also a translation.  What we want from you is the letter that Captain Snodgrass took from his mail box at the Rataplan this afternoon, and gave to you in the taxi on the way to the Chateau.”

She smiled incredulously.

“Absurd, sir!” she replied.  “Surely you are not serious!”

“Let me be entirely specific,” he returned “I’ll put all my cards on the table and play them open.”

“Double dummy, by all means!” she laughed, perching her lithe length on the arm of a chair, one slender foot swinging slowly back and forth.  “Your play, monsieur.”

“There is no need to go back farther than this morning,” he observed.  “We knew that you were to meet Captain Snodgrass and lunch with him at one o’clock at the Rataplan.  Your man Marston, when he visited Mr. Carpenter this morning, managed inadvertently to furnish the key-word of the Clephane letter.  Do you see whither your meeting with Snodgrass, an ex-officer of the Army, in view of the translation of the letter leads, Madeline?  Marston, I might remark, was quickly apprehended; if he made a copy of the letter, he had no opportunity to use it.  Well, you went to the Rataplan with Snodgrass—­every movement you two made, from the time you joined Snodgrass at the Chateau until I myself put you in my cab when you returned to the hotel, was observed by numerous and competent shadows.  We were convinced that you were to receive the formula—­”

“What formula, Guy?”

“The formula mentioned in the Clephane letter,” he explained; “which formula you received from Snodgrass during the ride back from the Rataplan to the Chateau.  He received it there by post, and got it from his box as you were leaving.  He even was foolish enough to open the original envelope, and to put the one enclosed, unopened in his pocket.  You immediately took a taxi for the Chateau.  My taxi was close behind yours; and I caught you as you were alighting and hurried you off to—­”

“This pleasant appointment!” she laughed.  “I suppose, Guy, you want the envelope and contents—­which you assume Captain Snodgrass transferred to me in the taxi; n’est-ce pas?”

“Exactly, Madeline.”

“And it’s three strong men and one woman against poor me,” she shrugged—­“unless Mrs. Clephane is merely a disinterested spectator.”

“I am always interested in what Mr. Harleston does,” Edith replied sweetly.

“Particularly when he is doing another woman,” was the retort.

“It depends somewhat on the woman done,” said Edith.

“Why are you here?” Mrs. Spencer laughed.

“To see the end of the affair of the cab-of-the-sleeping-horse.”

Mrs. Spencer shrugged and turned to Harleston.

“Do you expect to end it, Guy?” she asked.  “Because if you do, and this formulaic letter, that you think I have, will end it, I am sorry indeed to disappoint you.  I haven’t that letter, nor do I know anything as to it.”