"We are ready to fight," assented Miles and Ward. The situation was certainly an unusual one, and one they did not clearly understand; but theirs was the simple code of the mercenary soldier--they would fight for whoever hired them, and be loyal as long as their wages were paid. "Then there is no time to lose," exclaimed Zoro. "Already our blood grows thin. You must go back to the wrecked submarine and retrieve your weapons." "But how?" "There is a sending tube in the next compartment." * * * * * They followed Zoro through lofty rooms filled with amber light until they came to one wherein were assembled the rest of the Heads. Zoro spoke to them swiftly in a strange, flowing tongue. Then he conducted the two Americans to a crystal chamber at the end of the room and bade them enter it. The vibrant light caressed their limbs. "When I close this door," he said, "you will find yourselves back in the tunnel. Board one of the submarine-cars on the siding and proceed to the wreck." He gave them detailed instructions how to operate the car. "Then get your weapons and return. Do you understand?" They nodded. "The workers possess no arms the equal of machine-guns and bombs. They will be at your mercy. Remember that you are fighting for our lives and that, if you save them, your reward will be great. Fear nothing." The door closed. After a moment there was a blinding flash, a moment of swooning darkness, and then they were staring through transparent walls into the phosphorescent gloom of the underseas crypt. Suddenly, what they had recently undergone seemed the product of an illusion, a dream. Ward shook himself vigorously. "I guess it was real enough," he said. "Let us see if the car works." They ran out to the wreck and returned without trouble. The machine-gun was mounted for action and the gas-bombs slung over their shoulders in convenient bags. "All right," said Miles tensely, "let us go." Again they entered the crystal chamber; again there was the flash of light and the sensation of falling into darkest space. Then, in a moment it seemed, they were stepping into the hall from which they had fled pursued by the green men--only for the second time, to be confronted by a crowd of hostile giants. "Don't fire, Kid!" yelled Ward. "It's no use to kill them uselessly. Give them the bombs!" Disconcerted by the attack of tear-gas, the green men broke and fled. "After them," panted Ward: "we've got them on the run!" * * * * * Thrilling to the lust of battle, the two Americans emerged into an open square. They had little time to note the odd buildings and strange statues. Coming towards them with leveled weapons, the nature of which they did not know, was a band of short men--that is, short in comparison with the greenish giants. Behind this company appeared still another, and another. Tear-gas was useless to stop their onward rush. "All right," yelled Miles, "it's lead they want!"