It was an unusual hour for monks to be abroad. None the less, he seemed sure of himself, for he proceeded without hesitation to the altar, shrouded as it was in utter darkness, but for the light of one faint taper, which gleamed afar, like a star in the nocturnal heavens, driving the gloom a few paces from the carven stone. There the shrouded form seemed to melt into the very pall of night that weighed heavily upon the time-stained walls of the Mother Church of Rome. At first Tristan thought it was some belated penitent seeking forgiveness for his sins, but when the dark-robed form did not return he strode towards the altar to see if he might perchance be of assistance to him. When Tristan reached the altar steps he could discover no trace of a human being, though he searched every nook and corner and peered into every chapel, examined every shrine. Seized with a strange restiveness he began to pace up and down before the altar steps. He was far from feeling at ease. He remembered the warning of the Grand Chamberlain. He remembered the strange tales he had heard whispered of the Pontiff's prison house. Tristan suddenly paused. He thought he heard sibilant whispers and the low murmur of voices from behind the screen at the eastern transept of the Capella, and at once he began assembling the things in his mind which might beset him in the hour of darkness. The Chapel of the Most Holy Saviour of the Holy Stairs, the Scala Santa of the present day, adjoins the Lateran Church. At the period of which we write it was still the private chapel of the popes in the Patriarchium, and was called the Sancta Sanctorum on account of the great number of precious relics it enshrines. To this chapel Tristan directed his steps, oppressed by some mysterious sense of evil. By a judicious disposition of the men under his command he had, after a careful survey of the premises, placed them in such a manner that it would be impossible for any one to gain access to the stairs leading to the Pontiff's chamber. Had it been a hallucination of his senses conjured up by his sudden fear? Not a sound broke the stillness. Only the echoes of his own footsteps reverberated uncannily from the worn mosaics of the floor. In the dim distance of the corridors he saw a shadow moving to and fro. It was the guard before the entrance to a side-chapel of the Basilica. What caused Tristan to pause in the night gloom of the corridor leading to the Pontifical Chapel he did not know. He seemed as under a strange spell. At a distance from him of some five feet, in the decorated wall, there was a dark panel some two feet in height and of corresponding breadth, looking obliquely towards the Pontifical Chapel. The panel contained a small round opening, a spy-hole which communicated with a secret chamber in the thickness of the wall. A slight rustling noise came from behind the masonry. Tristan heard it quite distinctly. It suggested the passing of naked feet over marble.