Now, the very last thought that would occur to most people, if they want to penetrate into an underground passage, is to go first on to the roof; but then they are not school girls, and have forgotten all about these things, if, indeed, they ever knew them. To Aurore and her friends it was a matter of everyday knowledge that 'the longest way round is the shortest way home.' Had not Aurore sat breathless for days together over Mrs. Radcliffe's _Mysteries of Udolpho_, and her companions lain awake trembling at the recollections of Scotch or Irish ancestral ghosts? Why, even in the convent, where the great dormitories were filled with girls and the terrors of loneliness were unknown, did they not shudder sometimes in the dark in the certainty that they caught the echo of the sighs, the groans, the clanking of chains of the victim? As to whether it was always the same victim who had to be rescued, or whether in every generation a fresh victim was somehow mysteriously supplied, nobody inquired and nobody minded. * * * * * On the never-to-be-forgotten evening of Aurore's initiation into the company of the demons, she was conducted by the rest of the band into the oldest and most irregular part of the convent. At length they found themselves standing on a gangway with a wooden railing, ending in a little room, from which there was no outlet. By the light of their single taper they beheld a staircase below them, also with a wooden railing, and protected at the top by a strong oaken door. In order to get on to the staircase it was necessary to drop from one balustrade to the other--and the more experienced of the explorers strongly suspected that both of them were worm-eaten--while the staircase hung over black depths which no eye could penetrate. It was an adventure which required a good deal of courage, but not one of the girls flinched. Isabelle, one of the oldest of the demons, claimed her right to go first, and accomplished her dangerous feat with the resolution of a heroine. Mary followed with the calm of a gymnastic professor, the remainder as best they could, but somehow or other they all managed to arrive safely on the staircase. At the foot was another little hall or room, without door or window or issue of any kind; but this, for some strange reason, caused the girls more joy than regret. 'Certainly,' they said, 'nobody would make a staircase which went nowhere! There must be _some_ way out and we have got to find it.'