Stewart made no remark.  It was not the first occasion on which he had examined that place in an attempt to solve the mystery of the nocturnal whisperings.  He walked across to the wall, tapping it with his hand, while the faithful spaniel began sniffing in expectancy of something to bolt.  “There’s naething here, miss—­absolutely naething,” he declared, as they both examined the wall minutely.  Its depth did not admit of any chamber, for it was an inner wall; and, according to the gamekeeper’s statement, he had already tested it years ago, and found it solid masonry.

“If I went forward or backward, then the sounds were lost to me,” Gabrielle explained, much puzzled.

“Ay.  That’s juist what they a’ said,” remarked the keeper, with an apprehensive look upon his face.  “The Whispers are only h’ard at ae spot, whaur ye’ve juist stood.  I’ve seen the lady a’ in green masel’, miss—­aince when I was a laddie, an’ again aboot ten year syne.”

“You mean, Stewart, that you imagined that you saw an apparition.  You were alone, I suppose?”

“Yes, miss, I was alane.”

“Well, you thought you saw the Lady of Glencardine.  Where was she?”

“On the drive, in front o’ the hoose.”

“Perhaps somebody played a practical joke on you.  The Green Lady is Glencardine’s favourite spectre, isn’t she—­perfectly harmless, I mean?”

“Ay, miss.  Lots o’ folk saw her ten year syne.  But nooadays she seems to ha’e been laid.  Somebody said they saw her last Glesca holidays, but I dinna believe ’t.”

“Neither do I, Stewart.  But don’t let’s trouble about the unfortunate lady, who ought to have been at rest long ago.  It’s those weird whisperings I mean to investigate.”  And she looked blankly around her at the great, cyclopean walls and high, weather-beaten towers, gaunt yet picturesque in the morning sunshine.

The keeper shook his shaggy head.  “I’m afear’d, Miss Gabrielle, that ye’ll ne’er solve the mystery.  There’s somethin’ sae fatal aboot the whisperin’s,” he said, speaking in his pleasant Highland tongue, “that naebody cares tae attempt the investigation.  They div say that the Whispers are the voice o’ the De’il himsel’.”

The girl, in her short blue serge skirt, white cotton blouse, and blue tam-o’-shanter, laughed at the man’s dread.  There must be a distinct cause for this noise she had heard, she argued.  Yet, though they both spent half-an-hour wandering among the ruins, standing in the roofless banqueting hall, and traversing stone corridors and lichen-covered, moss-grown, ruined chambers choked with weeds, their efforts to obtain any clue were all in vain.

To Gabrielle it was quite evident that the old keeper regarded the incident of the previous night as a fatal omen, for he was most solicitous of her welfare.  He went so far as to crave permission to go to Sir Henry and put the whole of the mysterious facts before him.