Mr. Dane, in the moment’s breathless silence which followed, acknowledged to himself the perpetration of a rare mistake.  He had selected Philip to bear the brunt of his attack, believing him to be possessed of the weaker nerve.  Beatrice, who at the end of his last speech had sunk into a chair, white and terrified, an easy victim, had rallied now, inspired by Philip’s composure.

“You deny, then, that you are Mr. Philip Romilly?” the detective asked.

“I never heard of the fellow in my life,” Philip replied pleasantly, “but don’t go, Mr. Dane.  You can’t imagine how interesting this is to me.  You have sent me a most charming acquaintance,” he added, bowing to Beatrice, “and you have provided me with what I can assure you is almost pathetically scarce in these days—­a new and very dramatic idea.  Take a seat, won’t you, and chat with us a little longer?  Tell us how you came to think of all this?  I have always held that the workings of a criminologist’s brain must be one of the most interesting studies in life.”

Mr. Dane smiled enigmatically.

“Ah!” he protested, “you mustn’t ask me to disclose all my secrets.”

“You wouldn’t care to tell us a little about your future intentions?” Philip enquired.

Mr. Dane shook his head.

“It is very kind of you, Mr. Merton Ware,” he confessed, “to let me down so gently.  We all make mistakes, of course.  As to my future intentions, well, I am not quite sure about them.  You see, this isn’t really my job at all.  It isn’t up to me to hunt out English criminals, so long as they behave themselves in this city.  If an extradition order or anything of that sort came my way, it would, of course, be different.”

“Why not lay this interesting theory of yours before the authorities at Scotland Yard?” Philip suggested.  “I am sure they would listen with immense interest to any report from you.”

“That’s some idea, certainly,” the detective admitted, taking up his hat from the table.  “For the present I’ll wish you both good morning—­or shall I say an revoir?”

“We may look for the pleasure of another visit from you, then?” Philip enquired politely.

The detective faced them from the doorway.

“Sir,” he said to Philip, “I admire your nerve, and I admire the nerve of your old sweetheart, Miss Wenderley.  I am afraid I cannot promise you, however, that this will be my last visit.”

The door closed behind him.  They heard the shrill summons of the bell, the arrival of the lift, the clanging of the iron gate, and its subsequent descent.  Then Beatrice turned her head.  Philip was still smoking serenely, standing with his back to the mantelpiece, his hands in his pockets.  She rose and threw her arms around him.

“Philip!” she cried.  “Why, you are wonderful!  You are marvellous!  You make me ashamed.  It was only for a moment that I lost my nerve, and you saved us.  Oh, what idiots we were!  Of course he meant to watch—­that’s why he told me he was going to Chicago.  The beast!”