It was with a conscious effort that I shook myself out of this
morbidly reflective mood, on finding that we had crossed the common
and were come to the abode of my patient.

"I shall take a little walk," announced Eltham; "for I gather that you
don't expect to be detained long? I shall never be out of sight of the
door, of course."

"Very well," I replied, and ran up the steps.

There were no lights to be seen in any of the windows, which
circumstance rather surprised me, as my patient occupied, or had
occupied when last I had visited her, a first-floor bedroom in the
front of the house. My knocking and ringing produced no response for
three or four minutes; then, as I persisted, a scantily clothed and
half-awake maid-servant unbarred the door and stared at me stupidly in
the moonlight.

"Mrs. Hewett requires me?" I asked abruptly.

The girl stared more stupidly than ever.

"No, sir," she said: "she don't, sir; she's fast asleep!"

"But some one 'phoned me!" I insisted, rather irritably, I fear.

"Not from here, sir," declared the now wide-eyed girl. "We haven't got
a telephone, sir."

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 adamantine, but told him where he would
find the bag and once more set out across the moon-bright common, he
pursuing a westerly direction and I going east.

Some three hundred yards I had gone, I suppose, and my brain had been
very active the while, when something occurred to me which placed a
new complexion upon this second summons. I thought of the falsity of
the first, of the improbability of even the most hardened practical
joker practising his wiles at one o'clock in the morning. I thought of
our recent conversation; above all I thought of the girl who had
delivered the message to Eltham, the girl whom he had described as a
French maid--whose personal charm had so completely enlisted his
sympathies. Now, to this train of thought came a new one, and, adding
it, my suspicion became almost a certainty.

I remembered (as, knowing the district, I should have remembered
before) that there was no number 280 Rectory Grove.

Pulling up sharply, I stood looking about me. Not a living soul was in
sight; not even a policeman. Where the lamps marked the main paths
across the common nothing moved; in the shadows about me nothing
stirred. But something stirred within me--a warning voice which for
long had lain dormant.

What was afoot?

A breeze caressed the leaves overhead, breaking the silence with
mysterious whisperings. Some portentous truth was seeking for
admittance to my brain. I strove to reassure myself, but the sense of
impending evil and of mystery became heavier. At last I could combat
my strange fears no longer. I turned and began to run towards the
south side of the common--towards my rooms--and after Eltham.

I had hoped to head him off, but came upon no sign of him. An
all-night tramcar passed at the moment that I reached the high-road,
and as I ran around behind it I saw that my windows were lighted and
that there was a light in the hall.

My key was yet in the lock when my housekeeper opened the door.

"There's a gentleman just come, doctor," she began.

I thrust past her and raced up the stairs to my study.

Standing by the writing-table was a tall thin man, his gaunt face
brown as a coffee-berry and his steely grey eyes fixed upon me. My
heart gave a great leap--and seemed to stand still.

It was Nayland Smith!

"Smith!" I cried. "Smith, old man, by God, I'm glad to see you!"

He wrung my hand hard, looking at me with his searching eyes; but
there was little enough of gladness in his face. He was altogether
greyer than when last I had seen him--greyer and sterner.

"Where is Eltham?" I asked.

Smith started back as though I had struck him.

"Eltham!" he whispered--"_Eltham_! is Eltham here?"

"I left him ten minutes ago on the common."

Smith dashed his right fist into the palm of his left hand, and his
eyes gleamed almost wildly.

"My God, Petrie!" he said, "am I fated _always_ to come too late?"

My dreadful fears in that instant were confirmed. I seemed to feel my
legs totter beneath me.

"Smith, you don't mean--"

"I do, Petrie!" His voice sounded very far away. "Fu-Manchu is here;
and Eltham, God help him ... is his first victim!"