Close by the last turn of the turret staircase yawned the iron-sparred mouth of the dungeon, in which in its time many a notable prisoner had been immured.  It was closed with a huge grid of curved iron bars, each as thick as a man’s arm, cunningly held together by a gigantic padlock, the key of which was nightly taken to the sleeping-room of the Earl—­whether, as was now the case, the cell stood empty, or whether it contained an English lord waiting ransom or a rebellious baron expectant of his morning summons to the dule tree of the Black Douglas.

Then taking the master-key from his belt, Sholto unlocked the sparred gate leading from the salle de garde into the turret stair which was the sole communication with the upper floors of the castle.

Slowly, and with a step no louder than the beating of his own heart, he went upwards, glancing in midway upon the banquet hall, where the dim light from the postern without revealed a number of dark forms wrapped in slumber lying on the dining-table and on the floor; ascending yet higher he came to the floor where slept the Countess of Douglas, the Lady Sybilla, and in the Earl’s own chamber the Marshal de Retz, ambassador of the King of France.

Sholto stood a moment with his hand raised in a listening attitude, before he ventured to ascend those narrower stairs which led to the uppermost floor of all, on which were the chambers occupied by the little Maid Margaret and her companion and gossip Mistress Maud Lindesay.

He told himself that it was his duty to see to the safety of the whole castle; that he had special instructions to visit three times, during the course of each night of duty, all the passages and corridors of the fortress.  But nevertheless it needed all his courage to enable Sholto to perform the task which had been laid upon him.  As he dragged one foot after the other up the turret stairs, it seemed as if a leaden clog had been attached to each pointed shoe.

He had also a vague sense of being watched by presences invisible to him, but malign in their nature.  Again and again he caught himself listening for footsteps which seemed to dog his own.  He heard mysterious whisperings that flouted his utmost vigilance, and mocking laughter that lurked in unseen crevices and broke out so soon as he had passed.

Sholto set his hand firmly upon his sword handle and bit his lips, lest even to himself he should own his uneasiness.  It was not seemly that the captain of the Douglas guard should be frightened by shadows.

Passing the corridor which led towards the sleeping rooms of the maid and her companion, he ascended to the roof of the castle, thrusting aside the turret door and issuing upon the wide, open spaces with an assured step.  The cool breeze from the west restored him to himself in a moment.  The waning moon cast a pale light across the landscape, and he could see the tents on the castle island glimmer greyish white