“Mr. Sleuth, sir?  Mr. Sleuth!”

The lodger stopped and turned round.

He had been walking so quickly, and he was in so poor a physical condition, that the sweat was pouring down his face.

“Ah!  So it’s you, Mr. Bunting?  I heard footsteps behind me, and I hurried on.  I wish I’d known that it was you; there are so many queer characters about at night in London.”

“Not on a night like this, sir.  Only honest folk who have business out of doors would be out such a night as this.  It is cold, sir!”

And then into Bunting’s slow and honest mind there suddenly crept the query as to what on earth Mr. Sleuth’s own business out could be on this bitter night.

“Cold?” the lodger repeated; he was panting a little, and his words came out sharp and quick through his thin lips.  “I can’t say that I find it cold, Mr. Bunting.  When the snow falls, the air always becomes milder.”

“Yes, sir; but to-night there’s such a sharp east wind.  Why, it freezes the very marrow in one’s bones!  Still, there’s nothing like walking in cold weather to make one warm, as you seem to have found, sir.”

Bunting noticed that Mr. Sleuth kept his distance in a rather strange way; he walked at the edge of the pavement, leaving the rest of it, on the wall side, to his landlord.

“I lost my way,” he said abruptly.  “I’ve been over Primrose Hill to see a friend of mine, a man with whom I studied when I was a lad, and then, coming back, I lost my way.”

Now they had come right up to the little gate which opened on the shabby, paved court in front of the house—­that gate which now was never locked.

Mr. Sleuth, pushing suddenly forward, began walking up the flagged path, when, with a “By your leave, sir,” the ex-butler, stepping aside, slipped in front of his lodger, in order to open the front door for him.

As he passed by Mr. Sleuth, the back of Bunting’s bare left hand brushed lightly against the long Inverness cape the lodger was wearing, and, to Bunting’s surprise, the stretch of cloth against which his hand lay for a moment was not only damp, damp maybe from stray flakes of snow which had settled upon it, but wet—­wet and gluey.

Bunting thrust his left hand into his pocket; it was with the other that he placed the key in the lock of the door.

The two men passed into the hall together.

The house seemed blackly dark in comparison with the lighted-up road outside, and as he groped forward, closely followed by the lodger, there came over Bunting a sudden, reeling sensation of mortal terror, an instinctive, assailing knowledge of frightful immediate danger.

A stuffless voice—­the voice of his first wife, the long-dead girl to whom his mind so seldom reverted nowadays—­uttered into his ear the words, “Take care!”

And then the lodger spoke.  His voice was harsh and grating, though not loud.