cholocation?" Gregor said blankly. "You're going to teach me echolocation?" He was standing in a circular cave somewhere deep beneath Regalia with nothing but his mini flashlight.

Ripred slouched against a wall. Even for a rat, he had terrible posture. When he fought, everything in his body seemed to align and crackle with energy and power. The rest of the time, he wasn't much to look at. He reminded Gregor of one of those big baseball pitchers who kind of lumber around with their stomachs almost popping off their uniform buttons. You wouldn't bet they could make it around the bases without having to stop and catch their breath. But put them on the pitcher's mound and they'd fire off a hundred-mile-an-hour fastball that left the batter cross-eyed.

As if even slouching had been too much of an effort for him, Ripred slid down and lounged along the wall of the cave. "Yes, echolocation. Tell me what you know about it."

"I know bats use it. And dolphins, maybe. It's like radar. They make a sound and it bounces off of something and they can tell where it is without seeing it," said Gregor. "But people can't do that. I can't do that."

"Anybody can do it, to some extent. In the Overland, some blind people use it with excellent results," said Ripred. "The Underland humans don't give it much attention, but in this, they are fools. All the rest of us down here use it to some degree."

"You mean, the roaches and the spiders and —" started Gregor.

"All of us. Generations in the dark have helped the skill evolve. But if you could master even the most rudimentary elements of it, echolocation would be invaluable to you," said Ripred. "Say, for instance, if you lost your light in a cave with a rat." Gregor saw Ripred's tail coming, and his hand lifted to block it, but the rat was ahead of him this time. It was actually his hind foot that smacked the flashlight out of Gregor's hand and sent it spinning into the cave wall twenty feet away. The beam pointed into the stone, leaving them virtually in the dark.

Ripred's voice startled him. "And now I'm back here," the rat said from behind him. Gregor whipped around and, from somewhere off to his left, Ripred whispered, "Over here now."

The flashlight came spinning back across the floor and bumped into Gregor's feet. He picked it up and saw the rat was again slouching against the wall, on the far side of the cave from where the flashlight had been.

"So teach me," Gregor said, unnerved.

Ripred began by having him close his eyes and make a clicking sound, bouncing his tongue off the roof of his mouth. Then he had to listen very carefully to how it sounded. It was supposed to sound differently when he directed it toward a cave wall than when he directed it at Ripred. Then Ripred had him turn off his flashlight and click and listen and point it wherever it sounded like the rat might be. He really did try, but he'd only had about three hours of sleep in the last two days, plus all the craziness of being back in the Underland and the prophecy and the training and —

"Focus, Overlander! This could save your life!" Ripred snarled as Gregor miscalculated his position for the tenth time in a row.

"This is stupid, Ripred — it all sounds the same to me!" Gregor snapped back. "I can't do it, okay?"

"No, not okay. You will practice. Every time you get a chance down here and when you go home, if you get home, whenever you can," ordered Ripred. "You may not master it, but clearly you can only improve!"

"Okay. Fine. I'll practice. Are we done?" Gregor asked with some attitude. He'd about had it with the rat.

Suddenly Ripred's nose was inches from his own. The rat's eyes were narrowed in anger.

"Listen, Warrior," he hissed. "One day you will find that it matters not if you can hit three thousand blood balls if you cannot locate one in the dark. Understand?"

"Yeah," Gregor managed to get out. Ripred didn't move. "So, I'll practice. I will," said Gregor. "For real."

"Good. Now let's go get some sleep. We're both done in," said Ripred.

As they silently made their way back toward the city, Gregor wondered if Ripred would think twice about killing him. When they had been on the quest to get his dad, Ripred had kept him alive because they had mutual need: Gregor needed Ripred to find his dad. Ripred needed Gregor to help defeat King Gorger so that he could be the leader of the rats someday. Ripred must still need Gregor for "The Prophecy of Bane." But when Gregor had stopped being of use to the rat, would he be expendable?

Gregor's feet dragged as he climbed up the flights of stairs toward where he thought his bedroom was. It was very late here — probably about the time he'd come into the city the previous night — and everyone was asleep. He got lost and couldn't find anyone to give him directions. As he was wandering around, looking for a guard, he came upon the wooden door that shut off the room filled with Sandwich's prophecies.

The door was cracked open. This was strange; he thought they kept it locked all the time. Someone must be inside. He pushed the door open wider and stepped in. "Hello? Anybody in here?"

At first he thought the room was empty. The lamp was still lit under "The Prophecy of Bane," but no one appeared to be reading it. Then he heard a faint rustling sound in the far corner, and she stepped into the light.

"Oh!" Gregor jumped, not just because he was startled but because the sight of her was spooky. He had only seen Nerissa Once. She had been saying good-bye to her brother, Henry, as they left on the quest. He remembered she was very thin and seemed nervous. She had given him a copy of "The Prophecy of Gray" to take on his journey. Luxa had told him she could see the future or something.

If she had been thin before, she was now emaciated. Her eyes shone huge and hollow in the torchlight. Where Luxa had lilac circles under her eyes, Nerissa's were underscored with dark purple crescents. Her hair, which fell down far below her waist, was loose and tangled. Even though she was wrapped in a thick cloak, she acted like she was freezing.

"Oh, I'm sorry. Didn't mean to — I'm just — I was just looking for sleeping — I mean, looking for where I sleep. My bedroom. Sorry." Gregor started to back out of the room.

"No, wait, Overlander," Nerissa said in a tremulous voice. "Stay a moment."

"Oh, okay, sure," Gregor said, wishing very badly he could get out of there. "So, how've you been, Nerissa?" he said, and then cringed. How did he think she'd been?

"I have been unwell," Nerissa said tiredly. But it was not self-pitying, which somehow made it sadder.

"Look, I'm sorry about your brother, about Henry," said Gregor.

"I think it is best he is dead," said Nerissa.

"You do?" Gregor said, taken aback by her bluntness.

"When one considers the alternatives," said Nerissa. "Had he been successful in banding with the gnawers, we would all be dead. You, your sister, your father. All of my people. Henry, too. But, of course, I miss him greatly."

Well, she might be a wreck, but Nerissa was not afraid to look things in the eye. "Do you know why he did it?" Gregor ventured to ask.

"He was afraid. I know that. And I think somehow in his mind he felt that joining with the rats would give him the security he longed for," said Nerissa.

"He was wrong," said Gregor.

"Was he?" Nerissa said, and she smiled. Which was extra spooky.

"I thought so. Didn't you just say...if he'd got his way, we'd all be dead?" said Gregor. Maybe she was kind of crazy, after all.

"Oh, yes. His methods were undoubtedly flawed." Nerissa lost interest in their conversation and wandered over to "The Prophecy of Bane." Her bony fingers reached up and ran slowly across the letters, as if she were reading Braille. "And what of you, Warrior? Are you ready to face the Bane?"

The Bane. Ripred had said something about the Bane. "You mean...the prophecy?" Gregor asked, confused.

"Vikus did not tell you? We call the white rat 'the Bane,'" said Nerissa. "Do you know what that means?"

"Not exactly," Gregor admitted. - "It means a scourge," said Nerissa.

Wow, that was helpful. A scourge. "Still not clear," said Gregor.

"A calamity, an affliction." Nerissa searched his face for signs of understanding. "A very bad thing," she said finally.

"Oh, I got you," said Gregor. "Well, yeah, the rat. Vikus says I'm a threat to it or something. I'm supposed to help you guys kill it."

Nerissa looked bewildered. "Help us? Oh, no, Gregor, you must drain its light. See, it is written here." Her fingers rapidly passed over a line on the wall.

Will the warrior drain your light?

When Vikus had gone over the prophecy the night before, Gregor had been so consumed with the rats wanting to kill Boots, he hadn't focused much on this line. And Vikus hadn't elaborated. For the Underlanders, the word "light" was interchangeable with the word "life." So, when they talked about draining something's light, they meant killing it. The mission was to kill the Bane. He knew that. But Gregor had assumed the Underlanders would send a lot of soldiers with him. Trained soldiers.

The line pounded into his brain.

Will the warrior drain your light?

Gregor began to get a very bad feeling. "Oh, man," he said. "You mean, there's this giant white rat...and you guys expect me to...by myself...you mean, I'm supposed to..."