For a few moments I stood there, staring as foolishly as she; then abruptly I turned and descended the steps.  At the gate I stood looking up and down the road.  The houses were all in darkness.  What could be the meaning of the mysterious summons?  I had made no mistake respecting the name of my patient; it had been twice repeated over the telephone; yet that the call had not emanated from Mrs. Hewett’s house was now palpably evident.  Days had been when I should have regarded the episode as preluding some outrage, but to-night I felt more disposed to ascribe it to a silly practical joke.

Eltham walked up briskly.

“You’re in demand to-night, Doctor,” he said.  “A young person called for you almost directly you had left your house, and, learning where you were gone, followed you.”

“Indeed!” I said, a trifle incredulously.  “There are plenty of other doctors if the case is an urgent one.”

“She may have thought it would save time as you were actually up and dressed,” explained Eltham; “and the house is quite near to here, I understand.”

I looked at him a little blankly.  Was this another effort of the unknown jester?

“I have been fooled once,” I said.  “That ’phone call was a hoax—­”

“But I feel certain,” declared Eltham, earnestly, “that this is genuine!  The poor girl was dreadfully agitated; her master has broken his leg and is lying helpless:  number 280, Rectory Grove.”

“Where is the girl?” I asked, sharply.

“She ran back directly she had given me her message.”

“Was she a servant?”

“I should imagine so:  French, I think.  But she was so wrapped up I had little more than a glimpse of her.  I am sorry to hear that some one has played a silly joke on you, but believe me—­” he was very earnest —­“this is no jest.  The poor girl could scarcely speak for sobs.  She mistook me for you, of course.”

“Oh!” said I grimly, “well, I suppose I must go.  Broken leg, you said? —­and my surgical bag, splints and so forth, are at home!”

“My dear Petrie!” cried Eltham, in his enthusiastic way—­“you no doubt can do something to alleviate the poor man’s suffering immediately.  I will run back to your rooms for the bag and rejoin you at 280, Rectory Grove.”

“It’s awfully good of you, Eltham—­”

He held up his hand.

“The call of suffering humanity, Petrie, is one which I may no more refuse to hear than you.”

I made no further protest after that, for his point of view was evident and his determination adamant, but told him where he would find the bag and once more set out across the moonbright common, he pursuing a westerly direction and I going east.