“Who is he, sir, exactly, this Dr. Fu-Manchu?”

“I have only the vaguest idea, Inspector; but he is no ordinary criminal.  He is the greatest genius which the powers of evil have put on earth for centuries.  He has the backing of a political group whose wealth is enormous, and his mission in Europe is to pave the way!  Do you follow me?  He is the advance-agent of a movement so epoch-making that not one Britisher, and not one American, in fifty thousand has ever dreamed of it.”

Ryman stared, but made no reply, and we went out, passing down to the breakwater and boarding the waiting launch.  With her crew of three, the party numbered seven that swung out into the Pool, and, clearing the pier, drew in again and hugged the murky shore.

The night had been clear enough hitherto, but now came scudding rainbanks to curtain the crescent moon, and anon to unveil her again and show the muddy swirls about us.  The view was not extensive from the launch.  Sometimes a deepening of the near shadows would tell of a moored barge, or lights high above our heads mark the deck of a large vessel.  In the floods of moonlight gaunt shapes towered above; in the ensuing darkness only the oily glitter of the tide occupied the foreground of the night-piece.

The Surrey shore was a broken wall of blackness, patched with lights about which moved hazy suggestions of human activity.  The bank we were following offered a prospect even more gloomy—­ a dense, dark mass, amid which, sometimes, mysterious half-tones told of a dock gate, or sudden high lights leapt flaring to the eye.

Then, out of the mystery ahead, a green light grew and crept down upon us.  A giant shape loomed up, and frowned crushingly upon the little craft.  A blaze of light, the jangle of a bell, and it was past.  We were dancing in the wash of one of the Scotch steamers, and the murk had fallen again.

Discords of remote activity rose above the more intimate throbbing of our screw, and we seemed a pigmy company floating past the workshops of Brobdingnagian toilers.  The chill of the near water communicated itself to me, and I felt the protection of my shabby garments inadequate against it.

Far over on the Surrey shore a blue light—­vaporous, mysterious—­ flicked translucent tongues against the night’s curtain.  It was a weird, elusive flame, leaping, wavering, magically changing from blue to a yellowed violet, rising, falling.

“Only a gasworks,” came Smith’s voice, and I knew that he, too, had been watching those elfin fires.  “But it always reminds me of a Mexican teocalli, and the altar of sacrifice.”

The simile was apt, but gruesome.  I thought of Dr. Fu-Manchu and the severed fingers, and could not repress a shudder.

“On your left, past the wooden pier!  Not where the lamp is—­ beyond that; next to the dark, square building—­Shen-Yan’s.”

It was Inspector Ryman speaking.