This was a time for quick decisions and prompt action.  I weighed all the circumstances in the balance, and made the last vital choice of the night; I turned and ran toward the British Museum as though the worst of Fu-Manchu’s creatures, and not my allies the police, were at my heels!

No one else was in sight, but, as I whirled into the Square, the red lamp of a slowly retreating taxi became visible some hundred yards to the left.  My leg was paining me greatly, but the nature of the wound did not interfere with my progress; therefore I continued my headlong career, and ere the police had reached the end of Museum Street I had my hand upon the door handle of the cab—­for, the Fates being persistently kind to me, the vehicle was for hire.

“Dr. Cleeve’s, Harley Street!” I shouted at the man.  “Drive like hell!  It’s an urgent case.”

I leaped into the cab.

Within five seconds from the time that I slammed the door and dropped back panting upon the cushions, we were speeding westward toward the house of the famous pathologist, thereby throwing the police hopelessly off the track.

Faintly to my ears came the purr of a police whistle.  The taxi-man evidently did not hear the significant sound.  Merciful Providence had rung down the curtain; for to-night my role in the yellow drama was finished.

CHAPTER XXI

CRAGMIRE TOWER

Less than two hours later, Inspector Weymouth and a party of men from Scotland Yard raided the house in Museum Street.  They found the stock of J. Salaman practically intact, and, in the strangely appointed rooms above, every evidence of a hasty outgoing.  But of the instruments, drugs and other laboratory paraphernalia not one item remained.  I would gladly have given my income for a year, to have gained possession of the books, alone; for, beyond all shadow of doubt, I knew them to contain formula calculated to revolutionize the science of medicine.

Exhausted, physically and mentally, and with my mind a whispering-gallery of conjectures (it were needless for me to mention whom respecting) I turned in, gratefully, having patched up the slight wound in my calf.

I seemed scarcely to have closed my eyes, when Nayland Smith was shaking me into wakefulness.

“You are probably tired out,” he said; “but your crazy expedition of last night entitles you to no sympathy.  Read this; there is a train in an hour.  We will reserve a compartment and you can resume your interrupted slumbers in a corner seat.”

As I struggled upright in bed, rubbing my eyes sleepily, Smith handed me the Daily Telegraph, pointing to the following paragraph upon the literary page: