Jupiter seized her shoulders. "What do you mean?" "They--they run entirely underwater for ever so far and come out beneath the _Dra Dur_. The Anolyn built them that way in order to keep the humans from escaping through them." Jupiter swore in Lingua Galactica. "Suppose we go back to the streets. Can we reach the top of the wall? Does the sea come right up to its base?" "Yes," Tabak said with a shiver. Reiloc had stretched Lete out on the shelf. She was returning to consciousness, Jupiter saw; and he stooped, splashing water from the canal into the cave girl's face. Her eyes opened groggily. She pushed herself to her elbows, stared about her with the quick, terrified look of a wild thing. "You all right?" Jupiter asked. She let her head drop. "Yes. I couldn't help it, Jupiter. I--" "You'll do now," he said, not unkindly, and helped her to her feet. "Come on. We haven't any time to waste." When they reached the surface, Jupiter saw that night had fallen, and with it a thick fog had rolled in from the _Dra Dur_, choking the streets solid. It was like wet lamb's wool pressing against his eyeballs. They held hands to keep from becoming separated. Voices reached them out of the fog. Footsteps passed and faded away. At length they found a stair leading to the top of the sea wall, felt their way upward. * * * * * It seemed like hours to Jupiter before they reached the top. He lay flat on his belly, felt for the edge. He could see nothing below, but a faint lap-lap of wavelets against the base of the wall came up to him. "How deep is the water here?" "D-deep enough," Tabak whispered in a frightened voice. "All right, we'll jump." Lete gasped. There was a startled, protesting growl from Reiloc. "Jump blind, from here--from the top of the wall into the sea?" the Nehogan said. "Are you mad, Jupiter?" "Can you think of any other way to escape?" Tabak said in a queer, strained voice: "I'll jump. I'm not afraid--not too afraid." Jupiter heard her move toward the edge of the wall. "No! Wait! I'll go first--" But the Caligan girl had already leaped outward into the thick wet darkness. Jupiter felt suddenly cold all over. He knew that he would never smell salt water again without recalling the horrible expectancy of that moment. Time stood still. Then far below they heard a splash! "Tabak!" he called softly. He gave her time to rise to the surface. "Tabak!" He didn't dare lift his voice. There was no answer. Just the monotonous lap of the water against the sea wall. "God!" he thought. "She's hurt herself!" And he sprang outward into the encompassing blackness. He seemed to fall for an eternity before he struck. It was like hitting a plank. The jar ran up his legs. He went down, down, half-dazed. Then he was clawing frantically to the surface. He broke water. He could see nothing. It was like the bottom of a well. "Tabak! Tabak! Where are you?"