"In here," he called, and Joan thought of the baying of wolves running strong on a hot scent. She bit her lip, slipped into the blackness after him. "Jaro, where are you?" "This must be how they got him," he said from the darkness beside her. "When that gunman--the little one who was abducted along with the Red Witch, you remember--when he escaped he must have stumbled on these passages, I suppose that was the important information he had for Albert Peet." "They couldn't have gone very far," suggested Joan. "No," said Jaro. "Not very far, I hope." He closed the panel. At once the darkness gathered about them, pressed in on them from every side. It was so dark that the girl could bring her hand right up to her face without being able to distinguish a thing. * * * * * A ray of light jumped from the panel as Jaro extracted the plug, applied his eye to the aperture. He could see the back of the dead Mercurian leader crumpled across the desk and beyond him the open door into the vaulted antichamber. As he looked, a Mercurian, the priest who had been on guard at the entrance, appeared in the doorway. Other Mercurians were staring over the priest's shoulder. Consternation was written large across their usually impassive features. "Sehr Karfial Hodes!" the priest cried, and then uttered a string of Mercurian words quite unintelligible to the listening Jaro. Suddenly, it seemed to dawn on the priest that there had been foul play. He ran across the floor, turned up his dead leader's face. The benign, peaceful, half smile on the old Mercurian's lips seemed to belie his tragic murder. Jaro put back the plug. "We're in for it," he said grimly. "The Mercurians must believe that we murdered Karfial Hodes." "What will they do?" the girl asked in a small voice. "I don't imagine they'll pin any medals on us," he replied dryly. "Why did they have to kill Karfial Hodes?" There was a puzzled, tragic note in the girl's voice. "He was such a harmless old man." "Albert Peet can answer that question," Jaro said quietly. "In fact, he can answer a lot of questions that I intend to ask him. But where can I hide you?" "Hide me!" ejaculated Joan. "If you get three feet away I'll scream. I don't know why I should feel safer when you're here--I've been shot at, abducted and jailed since I met you--but I do." For a moment Jaro hesitated, then he fumbled for her wrist in the dark, found it. "Come on," he said. "We'll see where this passage leads." They crept ahead, encountered a stair, descended thirty-two steps. Again they felt their way along a passage, went down a second flight of steps. "If this keeps up we'll come out on the under side of Mercury," he said. "Ouch!" There was a dull thud. "What was that?" cried Joan.