Alarmed at this coarse language, and the threatening gestures that accompanied it, Isabelle started back and drew out Chiquita’s knife.

“Bravo!” cried the duke—­“here comes the traditional poniard.  We are being treated to a bit of high tragedy.  But, my fierce little beauty, if you are well up in your Roman history, you will remember that the chaste Mme. Lucretia did not make use of her dagger until after the assault of Sextus, the bold son of Tarquin the Proud.  That ancient and much-cited example is a good one to follow.”

And without paying any more attention to the knife than to a bee-sting, he had violently seized Isabelle in his arms before she could raise it to strike.

Just at that moment a loud cracking noise was heard, followed by a tremendous crash, and the casement fell clattering to the floor, with every pane of glass in it shattered; as if a giant had put his knee against it and broken it in; while a mass of branches protruded through the opening into the room.  It was the top of the tree that Chiquita had made such good use of as a way of escape and return.  The trunk, sawed nearly through by de Sigognac and his companions, was guided in its fall so as to make a means of access to Isabelle’s window; both bridging the moat, and answering all the purposes of a ladder.

The Duke of Vallombreuse, astonished at this most extraordinary intrusion upon his love-making, released his trembling victim, and drew his sword.  Chiquita, who had crept into the room unperceived when the crash came, pulled Isabelle’s sleeve and whispered, “Come into this corner, out of the way; the dance is going to begin.”

As she spoke, several pistol shots were heard without, and four of the duke’s ruffians—­who were doing garrison duty came rushing up the stairs, four steps at a time, and dashed into the room-sword in hand, and eager for the fray.

CHAPTER XVII.  THE AMETHYST RING

The topmost branches of the tree, protruding through the window, rendered the centre of the room untenable, so Malartic and his three aids ranged themselves two and two against the wall on either side of it, armed with pistols and swords—­ready to give the assailants a warm welcome.

“You had better retire, my lord duke, or else put on a mask,” whispered Malartic to the young nobleman, “so that you may not be seen and recognised in this affair.”

“What do I care?” cried Vallombreuse, flourishing his sword.  “I am not afraid of anybody in the world—­and besides, those who see me will never go away from this to tell of it.”

“But at least your lordship will place this second Helen in some safe retreat.  A stray bullet might so easily deprive your highness of the prize that cost so dear—­and it would be such a pity.”