"But It did, by heaven!" exclaimed the younger. And Glenn Farrell resumed his pacing the length of the Boukhara rug that carpeted the room. He made a gesture of futile rage, then resumed, "But how, Pierre--and why?" Pierre d'Artois twisted his mustache, shook his head again, and struck light to a cigarette. Farrell sank into the depths of his chair and retrieved the cigar butt he had laid on its arm. "We couldn't have slept on post without one of us being aware of it," resumed Farrell. His voice was monotonous from repetition of a statement so often made that he himself had begun to doubt it. "And if we had----" He regarded the waxen seals on the door. "Those seals couldn't have been duplicated, with your die locked in a bank vault each night. And she couldn't have escaped." "No, she could not," agreed d'Artois. "But some one--some _thing_--got in." "A weasel, a cat, a snake," enumerated Farrell, "might slip through those bars. Nothing larger. Certainly nothing large enough to--good God! _Listen!_" Grim and trembling they stood at the sealed door. They heard a moaning and a sobbing, then the screams of a woman seeking to stifle her outcry. "Give me that key!" demanded Farrell. He unlocked the door and flung it open, shattering the seals and breaking the cord that ran from panel to jamb. D'Artois followed him. They halted a few paces past the threshold. "Look, damn it, look!" As Farrell switched on the lights, he pointed at the woman who lay face down on the broad, canopied bed. She was writhing and moaning. At regular intervals she flinched as from a blow, then shuddered, and relaxed. "Lord! I can almost hear the whip," muttered Farrell. He leaped forward and thrust out his arm as if to ward off blows that flailed the girl's bare shoulders. Then he retreated, shaking his head. "If we can't see it, how can we stop it?" he muttered despairingly. They stood, fascinated and horrified, watching a lovely girl being flayed by an invisible scourge. They saw the red welts rising, crossing and recrossing her shoulders, and cropping up under the filmy silken folds of her nightgown. "Look at it! Her gown didn't move a hair's breadth, but the whip raised another welt! Pierre, it's impossible! That gown ought to be cut to pieces by that flogging. Or else nothing's really hitting her. Or else"--Farrell shook his head in bewildered despair--"or else we're both crazy as hoot-owls!" "_Tenez donc_," said the old Frenchman, taking his friend by the arm. Though he himself shrank in sympathy with the girl who writhed under the invisible lash, his voice was calmer than Farrell's. "Let us study this thing. And man or devil, in the end we will have his hide!" "You take the devils, Pierre, and give me a handful of whatever men you think are messed up in it! I'll--eh, what's that?" He knelt beside the bed, gestured to d'Artois. "Listen to that, Pierre!" he said in a tense whisper. "_Junayn' ash-Shaytan_ ..." they heard her say.