I thought the subject rather ill chosen, but recognized that my friend was talking more or less at random and in desperation; indeed, failing his reminiscences of Graywater Park, I think the demon of silence must have conquered us completely.

“Presumably,” I said, unconsciously speaking as though I feared the sound of my own voice, “this Spanish priest was confined at some time in the famous hidden chamber?”

“He was supposed to know the secret of a hoard of church property, and tradition has it, that he was put to the question in some gloomy dungeon ...”

He ceased abruptly; in fact the effect was that which must have resulted had the speaker been suddenly stricken down.  But the deadly silence which ensued was instantly interrupted.  My heart seemed to be clutched as though by fingers of ice; a stark and supernatural horror held me riveted in my chair.

For as though Nayland Smith’s words had been heard by the ghostly inhabitant of Graywater Park, as though the tortured priest sought once more release from his age-long sufferings—­there came echoing, hollowly and remotely, as if from a subterranean cavern, the sound of knocking.

From whence it actually proceeded I was wholly unable to determine.  At one time it seemed to surround us, as though not one but a hundred prisoners were beating upon the paneled walls of the huge, ancient apartment.

Faintly, so faintly, that I could not be sure if I heard aright, there came, too, a stifled cry.  Louder grew the the frantic beating and louder ... then it ceased abruptly.

“Merciful God!” I whispered—­“what was it?  What was it?”

CHAPTER XXXV

THE EAST TOWER

With a cigarette between my lips I sat at the open window, looking out upon the skeleton trees of the orchard; for the buds of early spring were only just beginning to proclaim themselves.

The idea of sleep was far from my mind.  The attractive modern furniture of the room could not deprive the paneled walls of the musty antiquity which was their birthright.  This solitary window deeply set and overlooking the orchard upon which the secret stair was said to open, struck a note of more remote antiquity, casting back beyond the carousing days of the Stuart monarchs to the troublous time of the Middle Ages.

An air of ghostly evil had seemed to arise like a miasma within the house from the moment that we had been disturbed by the unaccountable rapping.  It was at a late hour that we had separated, and none of us, I think, welcomed the breaking up of our little party.  Mrs. Oram, the housekeeper, had been closely questioned by Smith—­for Homopoulo, as a new-comer, could not be expected to know anything of the history of Graywater Park.  The old lady admitted the existence of the tradition which Nayland Smith had in some way unearthed, but assured us that never, in her time, had the uneasy spirit declared himself.  She was ignorant (or, like the excellent retainer that she was, professed to be ignorant) of the location of the historic chamber and staircase.