“You will remember that the men of Korakum told him the only way to gain entrance to Athensi was along the course of the subterranean river passing around the walls of Korakum. This river had its rise in the heart of the mountains behind Athensi, passed through the valley in which that city was situated, then disappeared again into the mountains and after passing through a series of natural caves or tunnels interspersed by open stretches of canyon, emerged into the plains of Korakum. Then it dived into the outer ring of mountains, never to reappear above ground. Probably, eventually, it reaches the Niger far to the west of us. “Well, it was my friend’s belief, based on hints dropped by one member of the exiled Athensians living in Korakum, that the heights above the hidden city could be gained by another method. Very long ago, he gathered, there had been another great road leading out from these heights to the desert, but the Athensians had destroyed it in order to preserve their isolation. It had been a great engineering feat to build it, but they had ruthlessly destroyed bridges across chasms and stone viaducts along the faces of steep cliffs, thus ensuring the impregnability of their city. However, Souchard understood, although his informant never would make a positive statement, that some of the exiles had been busy patching up the gaps in this road, flinging rude rope bridges across the chasms, and so on, to the end that men might pass single file. Doubtless, this was for purposes of accomplishing a coup of their own.” “And he was seeking that old road?” asked Jack. “Yes,” said Mr. Hampton. “And my guess is that, perhaps, he was discovered at it, and was tracked here and disposed of, in order that the secret might not escape.” “Wow,” cried big Bob, letting a long breath escape. “Pretty mess we’re planning to go into. I thought this was going to be a gentlemanly expedition, with overtures made to the Athensian rulers to let us come in and study their habits and history.” “And here we are stepping into a hornet’s nest,” supplemented Frank. Mr. Hampton smiled slightly. “Professor Souchard gave me to believe that it would be possible to approach the Athensians peaceably,” he said. “Otherwise I would not have undertaken this expedition, and brought you boys into danger, of course. But I’m beginning to believe now that he exaggerated the ease of approach, and minimized if he did not entirely ignore the dangers. Remember, he knew nothing much of the real Athensians. The exiles living in Korakum were his sole source of information. And, although he learned their language enough to converse with them haltingly, so short was his stay that there were many vital facts which he was unable to learn.