They had thought at first they were looting only empty temples--but, finding people there, had easily conquered them, though ruling them, he admitted, was another matter. As, for instance, yesterday, when the priests had interfered with his orders and carried his three chief captives off to sacrifice. "Where now, but for me, you would be food for their gods!" he ended. "And if you do not find my hospitality altogether to your liking, friends, remember that you came uninvited. In fact, if you will recall, you came despite my explicit warning!" * * * * * But since they were here, he told them, they might be willing to repay his good turn with another. Whereupon Von Ullrich launched into his proposal, which was that Professor Stevens place the _Nereid_ at his disposal for visiting the depths at the foot of the plateau, where lay the capital of the empire, he said--a magnificent metropolis known as the City of the Sun and modeled after the great Atlantean capital, the City of the Golden Gates, and the depository of a treasure, the greedy German believed, that was the ransom of the world. The professor frowned, and for a moment Larry thought he was going to remind their host that this was not a treasure hunt. "Why," he asked instead, "do you not use your own submarine for the purpose?" "Because for one thing, she will not stand the pressure, nor will our suits," was the reply. "And for another, she is already laden with treasure, ready for an--er--forced abdication!" with a sardonic laugh. "Then have you not enough gold already?" "For myself, yes. But there are my men, you see--and men who have glimpsed the treasures of the earth are not easily satisfied, Professor. But have no fear. You shall accompany us, and, by your aid, shall pay your own ransom." * * * * * Von Ullrich made no mention of the alternative, in case the aid was refused, but the ominous light Larry caught in his cold gray eyes spoke as clearly as words. So, since there was nothing else to do, Professor Stevens agreed. Whereupon the audience terminated and they were led from the presence of this arrogant German to another apartment, where they were to meet Captain Petersen and the crew of the _Nereid._ As they proceeded toward it, under guard, Larry wondered why Von Ullrich had even troubled to make the request, when he held it in his power to take the craft anyway. But after the first joyful moment of reunion, it was a mystery no longer, for Captain Petersen reported that immediately upon their capture, the commander of the U-boat had tried to force him to reveal the operation of the _Nereid_, but that he had steadfastly refused, even though threatened with torture. And to think, it came to Larry with a new twinge of shame, that he had suspected this gallant man of mutiny! * * * * *