“Do you accept my challenge, cavaliere?” she exclaimed, turning on Odo a glance confident of victory.

The Marquess meanwhile had approached the other nun with the intention of inducing her to unmask; but as Sister Mary of the Crucifix advanced to perform the same service for his friend, his irrepressible jealousy made him step hastily between them.

“Come cavaliere,” he cried, drawing Odo gaily toward the unknown nun, “since you have induced one of our fair guests to unmask perhaps you may be equally successful with the other, who appears provokingly indifferent to my advances.”

The masked nun had in fact retreated to a corner of the room and stood there, drawing her cloak about her, rather in the attitude of a frightened child than in that of a lady bent on a gallant adventure.

Sister Mary of the Crucifix approached her playfully.  “My dear Sister Veronica,” said she, throwing her arm about the other’s neck, “hesitates to reveal charms which she knows must cast mine in the shade; but I am not to be outdone in generosity, and if the Marquess will unmask his friend I will do the same by mine.”

As she spoke she deftly pinioned the nun’s hands and snatched off her mask with a malicious laugh.  The Marquess, entering into her humour, removed Odo’s at the same instant, and the latter, turning with a laugh, found himself face to face with Fulvia Vivaldi.  He grew white, and Mary of the Crucifix sprang forward to catch her friend.

“Good God!  What is this?” gasped the Marquess, staring from one to the other.

A glance of entreaty from Fulvia checked the answer on Odo’s lips, and for a moment there was silence in the room; then Fulvia, breaking away from her companion, fled out on the terrace.  The other was about to follow; but Odo, controlling himself, stepped between them.

“Madam,” said he in a low voice, “I recognise in your companion a friend of whom I have long had no word.  Will you pardon me if I speak with her alone?”

Sister Mary drew back with a meaning sparkle in her handsome eyes.  “Why, this,” she cried, not without a touch of resentment, “is the prettiest ending imaginable; but what a sly creature, to be sure, to make me think it was her first assignation!”

Odo, without answering, hastened out on the terrace.  It was so dark after the brightly lit room that for a moment he did not distinguish the figure which had sprung to the low parapet above the water; and he stumbled forward just in time to snatch Fulvia back to safety.

“This is madness!” he cried, as she hung upon him trembling.

“The boat,” she stammered in a strange sobbing voice—­“the boat should be somewhere below—­”

“The boat lies at the water-gate on the other side,” he answered.