As soon as the chauffeur espied them he whisked off the blanket;
Miss Erith said:  “Home!” and jumped in, and Vaux followed.

Deep under the fur robe they burrowed, shivering more from sheer excitement than from cold, and the car flew across to Fifth Avenue and then northward along deserted sidewalks and a wintry park, where naked trees and shrubs stood stark as iron in the lustre of the white electric lamps.

“That time the Secret Service made a mess of it,” he said with a nervous laugh.  “Did you notice Cassidy’s grin of triumph?”

“Poor Cassidy,” she said.

“I don’t know.  He butted in.”

“All the services are working at cross-purposes.  It’s a pity.”

“Well, Cassidy got his man.  That’s practically all he came for.  Evidently he never heard of a code-book in connection with Lauffer’s activities.  That diagonal cipher caught him.”

“What luck,” she murmured, “that you noticed that cook-book in the pantry!  And what common sense you displayed in smuggling it!”

“I didn’t suppose it was the book; I just took a chance.”

“To take a chance is the best way to make good, isn’t it?” she said, laughing.  “Oh, I am so thrilled, Mr. Vaux!  I shall sit up all night over my darling cipher and my fascinating code-book-dictionary.”

“Will you be down in the morning?” he inquired.

“Of course.  Then to-morrow evening, if you will come to my house, I shall expect to show you the entire letter neatly deciphered.”

“Fine!” he exclaimed as the car stopped before her door.

She insisted on sending him home in her car, and he was very grateful; so when he had seen her safely inside her house with the cook-book-dictionary clasped in her arms and a most enchanting smile on her pretty face, he made his adieux, descended the steps, and her car whirled him swiftly homeward through the arctic night.

CHAPTER II

THE SLIP

When Clifford Vaux arrived at a certain huge building now mostly devoted to Government work connected with the war, he found upon his desk a dictionary camouflaged to represent a cook-book; and also Miss Erith’s complete report.  And he lost no time in opening and reading the latter document: 

“Clifford Vaux, ESQ.,

“D.  C. of the E. C. D.,

“P.  I. Service. (Confidential)

“Sir: 

“I home the honour to report that the matter with which you have entrusted me is now entirely cleared up.

“This short preliminary memorandum is merely to refresh your memory concerning the particular case herewith submitted in detail.

“In re Herman Laufer: 

“The code-book, as you recollect, is Stormonth’s English Dictionary, XIII Edition, published by Wm. Blackwood & Sons, Edinburgh and London, MDCCCXCVI.  This book I herewith return to you.