“Strange,” I muttered; then:  “My name is Addison, constable,” I said, “and if any one should ask for me will you direct him to proceed to my house?” And I gave the man instructions respecting its whereabouts.

“I will,” answered the constable; and wishing him “good night,” I retraced my steps, curious respecting the matter, but not apprehensive as I well might have been—­and with no glimmering of the ghastly truth penetrating to my mind.

CHAPTER XXII

THE GRAY MIST

I was about half-way on my return journey when I heard a car racing along the road behind me, and as it came nearer I detected the fact that it was slowing down.  Ere I could turn: 

“Hi!  Mr. Addison!” hailed a voice.

I stopped, turned round, and there was Gatton leaning out of the car and staring towards me through the deepening dusk.

“Why, Gatton!” I said, walking up to him—­“I waited more than ten minutes for you, and then gave it up.”

“Waited for me?”

“Yes, by the police-box.”

He stared in evident wonder at me and then at the police chauffeur who drove the car.

“Whatever prompted you to do that?” he said.  “Coates must have given you the wrong message.  I said I would come to the house for you, not meet you in the street.”

Still I remained dense to the truth, and: 

“I know you did,” I replied.  “I refer to the second message.”

“I sent no second message.”

“What!”

“Get in,” cried Gatton shortly; “this wants explaining.”

I stepped into the car, and as it moved onward again I explained to the Inspector what had taken place.  As I talked I saw his expression grow darker and darker, until finally: 

“There’s something wrong!” he muttered.

“Then you did not inspire the message?”

“I know nothing whatever about it.  At the time you received it I was on my way from Crossleys.  I have been traveling for the last hour and a half.”

I stared at him very blankly.  The object of such a communication was difficult to imagine, and I knew of nothing incriminating in my possession, which might have tempted the assassin to lure me from the house whilst he obtained possession of it.

In ever-growing excitement I watched the houses slipping behind us as we swept along.  Then we came to the tree-lined expanse of road immediately leading to the cottage.  As the car stopped, I leaped out quickly, Gatton close upon my heels, and ran up the path to the door.

From certain indications with which I was familiar, I observed that Coates was out, whereby I concluded that he had set off to meet the mythical “man with a box.”  Not without apprehension I inserted the key in the lock and opened the door.

As I did so, I beheld a most singular spectacle.

The careful Coates had closed all the windows as usual before quitting the house, so that there was comparatively little draught along the corridor.  But as the door swung open I perceived a sort of gray fog-like vapor floating over the carpet about a foot in depth and moving in slightly sinuous spirals upward towards the opened door!