The rough foundation walls of the house, the massive stone wall built across the cellar to mask the secret chamber, the elaborate electric furnace, the huge hydraulic press, the workbench and tools, the powerful arc light pendent from the ceiling--half an eye would have convinced Nick that he occupied the workroom of that master craftsman whose chemical knowledge and inventive genius had given birth to a most marvelous production, long, earnestly, yet vainly, sought by others-- The production of an artificial diamond! Not until Nick heard the stone door forcibly closed, and its iron bolts shot violently into their sockets, did he pay serious attention to Cervera, the venomous Spanish vixen left to guard him. Then, as she swung round toward him, he took a sharper look at her darkly magnificent face, and was thrilled despite him by the extraordinary changes it had undergone. It had lost its beauty. Its olive flush had given place to a chalky whiteness. The radiance of her eyes had become a merciless glitter, like the glint cast from the eyes of a serpent. The reflection of a consuming passion for vengeance had transfigured her countenance, till it had become like the face of a fiend. Though Nick saw at a glance that his situation had taken on an unexpected and desperate phase, he suppressed any betrayal of it. He met the woman eye to eye, while she briefly paused and faced him, with a cruel smile curling her gray lips. "So I have you now, Nick Carter," she cried, with mocking significance. "Well, yes, in a way," admitted Nick, coolly. "I have you in my power," hissed Cervera, with a vicious display of satisfaction. "Ah! that's different," said Nick. "How different?" "That you have me in your power remains to be demonstrated." "Are we not alone here, you fool?" "Yes, very much alone." "And you helpless?" "Apparently." "If I wish, Nick Carter, I can kill you." "Then pray don't wish it," said Nick. "I am still too young to be heartlessly slain, even by so beautiful and accomplished a woman." "_Caramba!_ you mock me!" cried Cervera, darting toward him with eyes ablaze and her lithe figure quivering with passion. "You mock me!--you shall repent it! Perdition! you shall repent it!" "Is that so?" "You shall repent it, I say!" "In this world, or in the next?" inquired Nick, bent upon prolonging the scene as much as possible, with a hope that Chick might suddenly turn up. Cervera did not answer him immediately. She wheeled again and darted to the door, once more to make sure that she had secured its bolts. She was clad in the black dress in which she had escaped from Nick the previous night, the somber hue of which was relieved only by occasional flashes of her dainty white lace underskirts, as she swept quickly from place to place, with her lithe figure crouching at times, and her every movement as swift and impulsive as that of a startled leopard.