five o'clock
Malipieri listened to the end , and nodded thoughtfully . She was right , supposing that nothing had happened to Sassi and Masin ; but he knew his own man , and judged that he must have made some desperate attempt to stop the inflowing water in the outer chamber , and it was not impossible that poor old Sassi , in his devotion to Sabina , had made a mad effort to help Masin , and that they had both lost their lives together . If that had happened , there was no one to tell Volterra where Sabina was . Enquiries at Sassi 's house would be useless ; all that could be known would be that he had gone out between four and five o'clock , that he had called at the house in the Via Ludovisi , and that he and Sabina had driven away together . No doubt , in time , the police could find the cab they had taken , and the cabman would remember that they had paid him at the Palazzo Conti . But all that would take a long time . The porter knew nothing of their coming , and being used to Malipieri 's ways would not think of ringing at his door .