But as I fell I heard a scream above.  Smith’s revolver went hurtling through the air, and, hard upon it, went a black shape—­ flashing past the open window into the gulf of the night.

“The light!  The light!” I cried.

Guthrie ran and turned on the light.  Nayland Smith, his eyes starting from his head, his face swollen, lay plucking at a silken cord which showed tight about his throat.

“It was a Thug!” screamed Guthrie.  “Get the rope off!  He’s choking!”

My hands a-twitch, I seized the strangling-cord.

“A knife!  Quick!” I cried.  “I have lost mine!”

Guthrie ran to the dressing-table and passed me an open penknife.  I somehow forced the blade between the rope and Smith’s swollen neck, and severed the deadly silken thing.

Smith made a choking noise, and fell back, swooning in my arms.

When, later, we stood looking down upon the mutilated thing which had been brought in from where it fell, Smith showed me a mark on the brow—­ close beside the wound where his bullet had entered.

“The mark of Kali,” he said.  “The man was a phansigar—­ a religious strangler.  Since Fu-Manchu has dacoits in his service I might have expected that he would have Thugs.  A group of these fiends would seem to have fled into Burma; so that the mysterious epidemic in Rangoon was really an outbreak of thuggee—­on slightly improved lines!  I had suspected something of the kind but, naturally, I had not looked for Thugs near Rangoon.  My unexpected resistance led the strangler to bungle the rope.  You have seen how it was fastened about my throat?  That was unscientific.  The true method, as practiced by the group operating in Burma, was to throw the line about the victim’s neck and jerk him from the window.  A man leaning from an open window is very nicely poised:  it requires only a slight jerk to pitch him forward.  No loop was used, but a running line, which, as the victim fell, remained in the hand of the murderer.  No clew!  Therefore we see at once what commended the system to Fu-Manchu.”

Graham Guthrie, very pale, stood looking down at the dead strangler.

“I owe you my life, Mr. Smith,” he said.  “If you had come five minutes later—­”

He grasped Smith’s hand.

“You see,” Guthrie continued, “no one thought of looking for a Thug in Burma!  And no one thought of the roof!  These fellows are as active as monkeys, and where an ordinary man would infallibly break his neck, they are entirely at home.  I might have chosen my room especially for the business!”

“He slipped in late this evening,” said Smith.  “The hotel detective saw him, but these stranglers are as elusive as shadows, otherwise, despite their having changed the scene of their operations, not one could have survived.”

“Didn’t you mention a case of this kind on the Irrawaddy?” I asked.

“Yes,” was the reply; “and I know of what you are thinking.  The steamers of the Irrawaddy flotilla have a corrugated-iron roof over the top deck.  The Thug must have been lying up there as the Colassie passed on the deck below.”