Nita felt a strange, tremulous thrill sweep over her--was it ecstasy or a premonition of evil? Two gentlemen were standing on the deck of the yacht, and when they were safely on board Dorian introduced them to Nita as New York friends--Captain Van Hise and Mr. Irwin. They gazed in deepest admiration at the young girl's brilliant beauty, and, after a few moments' pleasant chatting, Captain Van Hise looked significantly at Dorian and observed: "If you will set me ashore here, Mountcastle, I shall be infinitely obliged to you." "With pleasure," the young man replied, and suddenly drew Nita away from them all into the little cabin. "I must leave you for a few minutes just to set my friend ashore. You will not mind waiting, will you, darling?" he asked, as he drew her to his breast and kissed her fondly. "It is strange you did not bring him ashore when you came for me," she answered. "You see he had not asked me then. The presence of women on board may have driven him to sudden desperation as it did me once upon a time," he replied mischievously. "Oh, I do not wish to alarm your friend. Let me return," she murmured, clinging to him. "No, no, my darling, forgive my foolish jest!" he cried, and strained her to him with a solemn, yearning passion. Blushing warmly, she escaped from his lingering caresses, and then he led her back on deck. "Mr. Irwin will amuse you while you are waiting for me," he said, and then shook hands with the gentleman ere he climbed down the yacht's side to the little boat. Captain Van Hise was carrying a black leather case, and he was very cheerful--two facts that would have impressed an initiated person. The two young women suspected nothing. Mr. Irwin did not look especially attractive to a young girl's eyes. He was more than middle-aged, and his attire had a clerical cut in keeping with his formal gray whiskers. His voice, when he essayed a remark, was nervous, and the slight attempt at conversation fell through soon, for a sudden shadow had fallen over Nita. In a few minutes she became very restless, and strained her eyes through the deep purple haze of twilight toward the shore. "It is time for Dorian to return, but I do not hear the oars yet," she ventured tremulously. At that moment there came across the water the sound of pistol-shots from the shore! Nita and Lizette both shrieked simultaneously, and sprung to their feet. Mr. Irwin also arose in alarm. Nita caught his arm in a convulsive grasp. "Oh, what is it? I am so frightened!" she shuddered, and just then the sound came again--two pistol-shots across the water. CHAPTER XV. A DUEL ON THE BEACH. Mr. Irwin was a nervous, timid man, and the two women clinging to him alarmed him almost as much as did the mysterious shots from the shore. He saw the captain of the yacht hovering near, and beckoned him frantically to his assistance. The jolly sailor approached and exclaimed: