The call of an owl sounded very clearly three times.

I knew that to mean that a messenger had come; but from whence or bearing what tidings I knew not.  My friend’s plans were incomprehensible to me, nor had I pressed him for any explanation of their nature, knowing him to be in that high-strung and somewhat irritable mood which claimed him at times of uncertainty—­when he doubted the wisdom of his actions, the accuracy of his surmises.  He gave no sign.

Very faintly I heard a clock strike the half-hour.  A soft breeze stole again through the branches above.  The wind I thought must be in a new quarter since I had not heard the clock before.  In so lonely a spot it was difficult to believe that the bell was that of St. Paul’s.  Yet such was the fact.

And hard upon the ringing followed another sound—­a sound we all had expected, had waited for; but at whose coming no one of us, I think, retained complete mastery of himself.

Breaking up the silence in a manner that set my heart wildly leaping it came—­ an imperative knocking on the door!

“My God!” groaned Weymouth—­but he did not move from his position at the window.

“Stand by, Petrie!” said Smith.

He strode to the door—­and threw it widely open.

I know I was very pale.  I think I cried out as I fell back—­ retreated with clenched hands from before that which stood on the threshold.

It was a wild, unkempt figure, with straggling beard, hideously staring eyes.  With its hands it clutched at its hair—­at its chin; plucked at its mouth.  No moonlight touched the features of this unearthly visitant, but scanty as was the illumination we could see the gleaming teeth—­ and the wildly glaring eyes.

It began to laugh—­peal after peal—­hideous and shrill.

Nothing so terrifying had ever smote upon my ears. 
I was palsied by the horror of the sound.

Then Nayland Smith pressed the button of an electric torch which he carried.  He directed the disk of white light fully upon the face in the doorway.

“Oh, God!” cried Weymouth.  “It’s John!”—­and again and again:  “Oh, God!  Oh, God!”

Perhaps for the first time in my life I really believed (nay, I could not doubt) that a thing of another world stood before me.  I am ashamed to confess the extent of the horror that came upon me.  James Weymouth raised his hands, as if to thrust away from him that awful thing in the door.  He was babbling—­prayers, I think, but wholly incoherent.

“Hold him, Petrie!”

Smith’s voice was low. (When we were past thought or intelligent action, he, dominant and cool, with that forced calm for which, a crisis over, he always paid so dearly, was thinking of the woman who slept above.)

He leaped forward; and in the instant that he grappled with the one who had knocked I knew the visitant for a man of flesh and blood—­a man who shrieked and fought like a savage animal, foamed at the mouth and gnashed his teeth in horrid frenzy; knew him for a madman—­knew him for the victim of Fu-Manchu—­ not dead, but living—­for Inspector Weymouth—­a maniac!