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.