It was a new aspect of the situation and one that afforded no room for comment; and so lost in thought did I become that the cab was outside the house for which I was bound ere I realized that we had quitted the purlieus of Wapping.  Yet I had had leisure to review the whole troop of events which had crowded my life since the return of Nayland Smith from Burma.  Mentally, I had looked again upon the dead Sir Crichton Davey, and with Smith had waited in the dark for the dreadful thing that had killed him.  Now, with those remorseless memories jostling in my mind, I was entering the house of Fu-Manchu’s last victim, and the shadow of that giant evil seemed to be upon it like a palpable cloud.

Cadby’s old landlady greeted me with a queer mixture of fear and embarrassment in her manner.

“I am Dr. Petrie,” I said, “and I regret that I bring bad news respecting Mr. Cadby.”

“Oh, sir!” she cried.  “Don’t tell me that anything has happened to him!” And divining something of the mission on which I was come, for such sad duty often falls to the lot of the medical man:  “Oh, the poor, brave lad!”

Indeed, I respected the dead man’s memory more than ever from that hour, since the sorrow of the worthy old soul was quite pathetic, and spoke eloquently for the unhappy cause of it.

“There was a terrible wailing at the back of the house last night, Doctor, and I heard it again to-night, a second before you knocked.  Poor lad!  It was the same when his mother died.”

At the moment I paid little attention to her words, for such beliefs are common, unfortunately; but when she was sufficiently composed I went on to explain what I thought necessary.  And now the old lady’s embarrassment took precedence of her sorrow, and presently the truth came out: 

“There’s a—­young lady—­in his rooms, sir.”

I started.  This might mean little or might mean much.

“She came and waited for him last night, Doctor—­from ten until half-past—­ and this morning again.  She came the third time about an hour ago, and has been upstairs since.”

“Do you know her, Mrs. Dolan?”

Mrs. Dolan grew embarrassed again.

“Well, Doctor,” she said, wiping her eyes the while, “I do.  And God knows he was a good lad, and I like a mother to him; but she is not the girl I should have liked a son of mine to take up with.”

At any other time, this would have been amusing; now, it might be serious.  Mrs. Dolan’s account of the wailing became suddenly significant, for perhaps it meant that one of Fu-Manchu’s dacoit followers was watching the house, to give warning of any stranger’s approach!  Warning to whom?  It was unlikely that I should forget the dark eyes of another of Fu-Manchu’s servants.  Was that lure of men even now in the house, completing her evil work?

“I should never have allowed her in his rooms—­” began Mrs. Dolan again.  Then there was an interruption.