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 in 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 toward the south side of the common—­toward 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 into my study.

Standing by the writing-table was a tall, thin man, his gaunt face brown as a coffee-berry and his steely gray 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 grayer than when last I had seen him—­grayer 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.