"And what time did Mrs. Prentice leave?"

"A few minutes after I did. She was just going up for her wraps as I came downstairs at eleven o'clock."

"You are certain that she was there all evening—that she didn't slip out for half an hour or so?"

"Of course I'm sure, Mell," the girl replied, a trace of petulance in her voice. "Why all the questions? Do you suspect the wife of the Third Assistant Secretary of State of robbing a bank?"

"Not a bank," Taylor admitted, "but it happens that the safe in her husband's office was opened last night and a highly important slip of paper abstracted. What's more, the watchman on duty in the building is ready to swear that Mrs. Prentice came in shortly before nine-thirty, and went out some five or ten minutes later, stating that her husband had evidently finished his work and left."

"That's impossible! No matter what the watchman says, there are a score of people who dined with Mrs. Prentice last evening and who know that she didn't leave the Westovers' until after eleven. Dinner wasn't over by nine-thirty, and she couldn't have gotten to the State Department and back in less than twenty minutes at the inside. It's ridiculous, that's all!"

"But the watchman!" exclaimed Taylor. "He knows Mrs. Prentice and says he couldn't miss that green-and-fur coat of hers in the dark. Besides, she spoke to him as she was leaving."

Madelaine James was silent for a moment, and a tiny frown appeared between her eyes, evidence of the fact that she was doing some deep thinking.

Then: "Of course she spoke! Anyone who would go to the trouble of copying Mrs. Prentice's distinctive cloak would realize that some additional disguise was necessary. Last night, if you remember, was quite cold. Therefore it would be quite natural that the woman who impersonated Mrs. Prentice should have her collar turned up around her face and probably a drooping hat as well. The collar, in addition to concealing her features, would muffle her voice, while the watchman, not suspecting anything, would take it for granted that the green cloak was worn by the wife of the Under Secretary—particularly when she spoke to him in passing."

"You mean, then, that some one deliberately impersonated Mrs. Prentice and took a chance on getting past the watchman merely because she wore a cloak of the same color?"