Nayland Smith began stuffing mixture into the hot pipe-bowl, and dropping an almost equal quantity on the floor.

“I cannot rest, Petrie,” he said.  “I am itching to get to work.  Yet, a false move, and—­” He lighted his pipe, and stood staring from the window.

“I shall, of course, take a needle-syringe with me,” I explained.

Smith made no reply.

“If I but knew the composition of the drug which produced the semblance of death,” I continued, “my fame would long survive my ashes.”

My friend did not turn.  But: 

“She said it was something he put in the wine?” he jerked.

“In the wine, yes.”

Silence fell.  My thoughts reverted to Karamaneh, whom Dr. Fu-Manchu held in bonds stronger than any slave-chains.  For, with Aziz, her brother, suspended between life and death, what could she do save obey the mandates of the cunning Chinaman?  What perverted genius was his!  If that treasury of obscure wisdom which he, perhaps alone of living men, had rifled, could but be thrown open to the sick and suffering, the name of Dr. Fu-Manchu would rank with the golden ones in the history of healing.

Nayland Smith suddenly turned, and the expression upon his face amazed me.

“Look up the next train to L—!” he rapped.

“To L—?  What—?”

“There’s the Bradshaw.  We haven’t a minute to waste.”

In his voice was the imperative note I knew so well; in his eyes was the light which told of an urgent need for action—­ a portentous truth suddenly grasped.

“One in half-an-hour—­the last.”

“We must catch it.”

No further word of explanation he vouchsafed, but darted off to dress; for he had spent the afternoon pacing the room in his dressing-gown and smoking without intermission.

Out and to the corner we hurried, and leaped into the first taxi upon the rank.  Smith enjoined the man to hasten, and we were off—­ all in that whirl of feverish activity which characterized my friend’s movements in times of important action.

He sat glancing impatiently from the window and twitching at the lobe of his ear.

“I know you will forgive me, old man,” he said, “but there is a little problem which I am trying to work out in my mind.  Did you bring the things I mentioned?”

“Yes.”

Conversation lapsed, until, just as the cab turned into the station, Smith said:  “Should you consider Lord Southery to have been the first constructive engineer of his time, Petrie?”

“Undoubtedly,” I replied.

“Greater than Von Homber, of Berlin?”

“Possibly not.  But Von Homber has been dead for three years.”

“Three years, is it?”

“Roughly.”

“Ah!”

We reached the station in time to secure a non-corridor compartment to ourselves, and to allow Smith leisure carefully to inspect the occupants of all the others, from the engine to the guard’s van.  He was muffled up to the eyes, and he warned me to keep out of sight in the corner of the compartment.  In fact, his behavior had me bursting with curiosity.  The train having started: