"I hope it is strong," he murmured.

Then he mounted lightly up in the darkness, until he stood on the sill of the narrow doorway, when he reached forward his hand to assist his slower comrade in mounting, but she sprang past him without availing herself of his aid. In a low voice she begged pardon for preceding him. Then walked up and up a winding stone staircase, on whose steps there was barely room for two to pass each other. She pushed open a door and allowed some light to stream through on the turret stair, which disappeared in the darkness still further aloft.

The king found himself in a large square apartment either on the first or second story. It appeared in some sort to be a lady's boudoir, for the benches were cushioned and comfortable, and there were evidences, about on small tables, of tapestry work and other needle employment recently abandoned.

"Will your majesty kindly be seated," said the girl. "I must draw up the ladder, close the postern door, and then inform my lady that you are here."

She went out by the way they had entered and shut the door with a force that seemed to the king unnecessary, but he caught his breath an instant later as his quick ear seemed to tell him that a bolt had fallen. He rose at once, tried to open the door, and discovered it was indeed barred on the outside. One other exit remained to be tested; a larger door evidently communicating with another room or passage; that also he found locked. He returned to the middle of the room and stood there for a few moments with knitted brow.

"Trapped, Jamie, my lad! Trapped!" he muttered to himself. "Now what object can my mother have in this? Does she expect by such childish means to resume her authority over me? Does she hope that her third husband shall rule Scotland in my name as did her second, with me a prisoner? By Saint Andrew, no!"

The king seized a bench, raised it over his head and crashed it in bits against the larger door with a noise that reverberated through the castle.

"Open!" he cried; "open instantly!"

Then he paused, awaiting the result of his fury. Presently he thought he heard light footsteps coming along the passage and an instant later the huge key turned slowly in the lock. The door opened, and to his amazement he saw standing before him with wide frightened eyes, his guide, but dressed now as a lady.

"Madam," said the king sternly, "I ask you the meaning of this pleasantry?"

"Pleasantry," echoed the girl, staring at him with her hand upon a huge iron key, alert to run if this handsome maniac, strewn round by the wreckage of the bench he had broken, attempted to lay hands on her.

"Pleasantry?" she repeated; "that is a question I may well ask you.

Who are you, sir, and what are you doing here?"

"Who I am, and what I am doing here, you know very well, because you brought me here. A change of garb does not change a well-remembered face," and the king bowed to his visitor with a return of his customary courtliness, now that his suspicions were allayed, for he knew how to deal with pretty women. "Madam, there is no queen in Scotland, but you are queen by right of nature, and though you doff your gown, you cannot change your golden crown."

The girl's hand unconsciously went up to her ruddy hair, while she murmured more to herself than to him,--

"This is some of Catherine's work."

"Catherine was your name in the forest, my lady, what is your name in the castle?"

"Isabel is my name in castle and forest alike. You have met my twin sister, Catherine. Why has she brought you here?"

"Like an obedient son, I am here at the command of my honourable mother; and your sister--if indeed goddesses so strangely fair, and so strangely similar can be two persons--has gone to acquaint my mother of my arrival."

The girl's alarm seemed to increase as the king's diminished. Trouble, dismay, and fear marred her perfect face, and as the king scrutinised her more minutely, he saw that the firm mouth and the resolute chin of her sister had no place in the more softened and womanly features of the lady before him.

"Your mother? Who is she?"

"First, Margaret Tudor, daughter of the King of England, second, Margaret Stuart, wife of the King of Scotland, third, Margaret Douglas, ill mate of the Earl of Angus; fourth, and let us hope finally, Margaret Stuart again, spouse of Lord Methven, and owner of this castle."

The girl swayed as if she would fall, all colour struck suddenly from her face. She leaned, nearly fainting, against the stone wall, passing her hand once or twice across her terror-filled eyes.

"Great God," she moaned, "do not tell me that you are James, King of Scotland, here, and alone, in this den of Douglases!"

"Douglas!" cried the king roused at the hated name. "How can there be Douglases in the Castle of Doune; my mother's house, constabled by my friend, young Stuart."

"Your mother's house?" said the girl with an uncanny laugh. "When has the Lady Margaret set foot in Doune? Not since she was divorced from my uncle, Archibald Douglas, Earl of Angus! And the constable? Aye, the constable is in Stirling. Doune Castle stands gloomy and alone, but in Stirling with the young king, there are masques, and hunting and gaiety. Young Stuart draws the revenues of his charge, but pays slight attention to the fulfilment of his duty."

"You are then Isabel Douglas? And now, to echo your own question, how came you here? If this is a den of Douglases, as you say, how comes my mother's castle to be officered by the enemies of her son?"

"That you ask such a question shows little foresight or knowledge of men. When your first step-father, and my uncle, Archibald Douglas, had control of this castle through your mother's name, he filled it with his own adherents."

"Naturally; nepotism was a well-known trait of my domineering step-father, which did not add to his popularity in Scotland. Who can get office, or justice against a Douglas? was their cry. But did not young Stuart, when he was made constable, put in his own men?"

"The constable cares nothing for this stronghold so long as it furnishes money which he may spend gaily in Stirling."

"I see. So you and your sister found refuge among your underlings? and where so safe from search as within the king's mother's own fortress, almost under the shadow of Stirling? An admirable device. Why then do you jeopardise your safety by letting me into the secret?"

The girl sighed deeply with downcast eyes, then she flashed a glance at him which had something in it of the old Douglas hauteur.

"I fear," she said, "that it is not our safety which is jeopardised."

"You mean that I am in danger?"

"The same stronghold which gives immunity to a family of the Red Douglases can hardly be expected to confer security upon James the Fifth, their persecutor."

"No. Certainly that would be too much to expect. Are you then in this plot against me, my lady?"

"I have not heard of any plot. If there is one I know nothing of it. I merely acquaint you with some hint of my fears."

"Then I charge you as a loyal subject of the lawful king, to guide me from this stronghold, into which I have been cozened by treachery and falsehood."

Catherine, who had entered silently and unnoticed through the smaller door, now stepped forward, drew her sister into the room, took out the huge key, closed the door and locked it, then turned fiercely to the king. Her beautiful white right arm was bare to the elbow, the loose sleeve rolled up, and in her hand she held a dagger. With her back against the newly locked door, she said,--

"I'll be your majesty's guide from this castle, and your perjured soul shall find exit through a postern gate made by my dagger!"

"Oh, Catherine, Catherine," sobbed Isabel, weeping in fear and horror of the situation, "you cannot contemplate so awful a deed, a murder so foul, for however unworthy he may be, he is still the king."

"What is there foul in ridding the world of a reptile such as he? How many innocent lives has he taken to encompass his revenge? How many now of our name are exiled and starving because of his action? I shall strike the blow with greater surety, for in killing him I extinguish his treacherous race."

"No good can come from assassination, Catherine."

"What greater evil can spring from his death than from his life?"

"His killing will not bring back those whom he has slain; it will not cause our banished kinsmen to return. It will be a murder for revenge."

"And not the first in Scotland," said Catherine grimly.

The king had once more seated himself, and now, resting his chin on his open palm, listened to the discussion with the interested bearing of one who had little concern with its result. A half amused smile wreathed his lips, and once or twice he made a motion as if he would intervene, but on second thoughts kept silent.

"Do not attempt this fell deed, dear sister," pleaded Isabel earnestly. "Let us away as we intended. The horses are ready and waiting for us. Our mother is looking for our coming in her room. The night wears on and we must pass Stirling while it is yet dark, so there is no time to be lost. Dear sister, let us quit Scotland, as we purposed, an accursed land to all of our name, but let us quit it with unstained hands."

"Isabel, darling," said Catherine in a low voice that quavered with the emotion caused by her sister's distress and appeal, "what unlucky chance brought you to this fatal door at such a moment? Can you not understand that I have gone too far to retreat? Who, having caged the tiger, dare open again the gate and set him free? If for no other reason, the king must die because he is here and because I brought him here. Open the door behind you, Isabel, go down the circular stair, and at the postern step you will find the rope ladder by which I ascended. Get you to the courtyard and there wait for me, saying nothing."

"Catherine, Catherine, the king will pardon you. He will surely forgive what you have done in exchange for his life."