“They might induce them to leave them behind, when they went out to take their pleasures among the maids of the Lawnmarket,” said Sholto.

“Not their swords,” said the Earl, “it needed all your lord’s commands to make yours quit your side.  I warrant these fellows will give an excellent account of themselves.”

Presently the night fell darker, and a smurr of rain drifted over from the edges of Pentland, mostly passing high above, but with lower fringes that dragged, as it were, on the Castle Rock and the Hill of Calton.

The three young men were still silently looking out when suddenly from the darkness underneath there came a low voice.

“’Ware window!” it said, “stand back there above.”

To Sholto the words sounded curiously familiar, and almost without thinking what he did, he seized the Earl and his brother and dragged them away from the wide space of the lattice, which opened into the summer’s night.

“’Ware window!” came again the cautious voice from far below.  Sholto heard the whistle and “spat” of an arrow against the wall without.  It must have fallen again, for the voice ’came a third time—­“’Ware window!”

And on this occasion the archer was successful, guided doubtless by the illumination of the lantern the guard had hung on a nail, and whose flicker would outline the lattice faintly against the darkness of the wall.

An arrow entered with a soft hiss.  It struck beyond them with a click, and its iron point tinkled on the floor, the plaster of the opposite wall not holding it.

Sholto scrambled about the floor on hands and knees till he found it.  It was a common archer’s arrow.  A cord was fastened about it, and a note stuck in the slit along with the feather.

“It is my brother Laurence,” whispered Sholto.  “I warrant he is beneath with a rope and a posse of stout fellows.  We shall escape them yet.”

But even as he raised the letter to read it by the faint blue flicker of the lantern, there came a cry of pain from within the castle.  It was a woman’s voice that cried, and at the sound of pleading speech in some chamber above them, William Douglas started to his feet.

The words were clear enough, but in a language not understood by Sholto MacKim.  They seemed intelligible enough, however, to the Earl.

“I knew it,” he cried; “the false hounds have imprisoned her also.  It is Sybilla’s voice.  God in heaven—­they are torturing her!”

He ran to the door and shook it vehemently.

“Ho!  Without there!” he cried imperiously, as if in his own Castle at Thrieve.

But no one paid any attention to his shouts, and presently the woman’s voice died down to a slow sobbing which was quite audible in the room beneath, where the three young men listened.

“What did she say?” asked David, presently, of his brother, who still stood with his ear to the door.