“I will do so, Francisco, at once.  I will send to two of my officers at the port, and tell them to pick out a dozen men on whom they can rely, to proceed to Botonda, and to watch closely everyone who enters or leaves the house, without at the same time making themselves conspicuous.  At any rate, they will be handy there in case Mocenigo’s friends attempt to rescue him by force, which might be done with success, for the house he occupies stands at a short distance out of the town, and the official in charge of Mocenigo has only eight men with him.

“Yes, your advice is excellent, and I will follow it at once.  Should any other idea occur to you, pray let me know it immediately.  You saved my daughters once, and although I know there is no reason why it should be so, still, I feel a sort of belief that you may, somehow, be instrumental in their again being brought back to me.”

“I will do my best, sir, you may depend upon it,” Francis said earnestly.  “Were they my own sisters, I could not feel more strongly interested in their behalf.”

Francis spent the next week almost entirely in his gondola.  Starting soon after daybreak with Giuseppi, he would row across to the villages on the mainland, and make inquiries of all sorts there; or would visit the little groups of fishermen’s huts, built here and there on posts among the shallows.  He would scan every house as he passed it, with the vague hope that a face might appear at the window, or a hand be waved for assistance.  But, during all that time, he had found nothing which seemed to offer the slightest clue, nor were the inquiries set on foot by Signor Polani more successful.  Every piece of information which seemed to bear, in the slightest degree, upon the affair was investigated, but in no case was it found of the slightest utility.

One evening he was returning late, tired by the long day’s work, and discouraged with his utter want of success, when, just as he had passed under the Ponto Maggiore, the lights on the bridge fell on the faces of the sitters in a gondola coming the other way.  They were a man and a woman.  The latter was closely veiled.  But the night was close and oppressive, and, just at the moment when Francis’ eyes fell upon her, she lifted her veil for air.  Francis recognized her instantly.  For a moment he stopped rowing, and then dipped his oar in as before.  Directly the other gondola passed through the bridge behind him, and his own had got beyond the circle of light, he swept it suddenly round.

Giuseppi gave an exclamation of surprise.

“Giuseppi, we have luck at last.  Did you notice that gondola we met just now?  The woman sitting in it is Castaldi, the woman who betrayed the signoras.”

“What shall we do, Messer Francisco?” Giuseppi, who had become almost as interested in the search as his master, asked.  “There was only a single gondolier and one other man.  If we take them by surprise we can master them.”