"Seems to me," said a quiet voice, "that now would be a great first lesson. Dive in and I'll do the rest."

Cyrus glanced behind him. Off the end of the jetty, barely visible in the waves, Llewellyn Douglas clicked his false teeth.

"Tigs," Cyrus whispered. "Dennis. Follow me. No questions. Just jump in and dive down. Get below the surface." He picked up his jacket and slung it on. He'd ditch it if he had to swim far, but he didn't want to. He glanced at his boots. Too awkward.

"Mr. Cyrus," Dennis said. "I can't-"

"Now!" said Cyrus. He grabbed Dennis by the wrist and turned to grab Antigone. His sister was already gone, kicking in the air above the water.

Cyrus planted his bare foot on the end of the jetty and pushed off. Dennis's weight tugged him backward, his feet swung up, and he landed flat on his back in the water.

Dennis landed on top of him.

Cyrus thrashed, tangled in Dennis. Tangled in cape. And then someone was pulling his arm, pulling him down. Quickly. Smoothly. Something big and dark and rough thumped against his chest. He grabbed on to it with his free arm, and it felt like a tree trunk wrapped in sandpaper-a muscled, swimming tree trunk. The bubbles cleared and Cyrus looked around. The skeleton in underwear had his left arm hooked over one of the big shark's pectoral fins. With his right, he was dragging Cyrus by the wrist. On the other side of the shark, Cyrus glimpsed his sister clutching a fin. Dennis and his cape were dragging from Antigone's ankles.

The shark's tail thumped Cyrus in the ribs, and Llewellyn Douglas tugged him up to the pectoral fin. Cyrus grabbed on, and then the scrawny man threw his arms around the cruising shark's back, slid himself up and forward of the dorsal fin, and then patted the shark's gills.

The tail swept and the shark surged, diving into deep water.

Ben Sterling stood at the end of the jetty, staring at the water. They were kids, brand-new Acolytes. They couldn't have gone far. Dead or alive, they'd be bobbing up soon.

"Big B?" one of the men asked.

"I have some dynamite," said another.

Sterling shook his head. "Get back to hunting the Polygon boy. I'll stay here."

The men turned and began walking off the jetty. "Double time!" Sterling yelled. The men jumped into a jog.

Sterling pushed the fishing-poled wheelchair onto the middle of the jetty and eased himself into it. "Llewellyn Douglas," he said, scanning the waves. "You're down there, too?" After a moment, a smile rustled beneath his beard, and he stood back up. "Old dog," he said quietly. "Old trick."

The wind surged, ringing Ben Sterling's bells and shivering his beard. Chuckling to himself, he hurried off the jetty.

Cyrus felt the water pressure grow as they slid deeper and deeper down the face of the shelf. Suddenly, the shark veered into it, Cyrus's legs dragged across stone, and the last of the light died.

A rock grazed Cyrus's head. His foot. They were moving through a tunnel. He tucked tight against the shark's body and let himself release most of his air. Dennis was yelling. Bubbling.

Cyrus tried to relax, to forget about what he was doing, to forget about his panicking lungs and his bulging eyes.

The shark thrashed and Cyrus nearly slipped off. They were climbing, winding, ascending.

Time slowed down. Limbs became lead, and then Cyrus felt his foot splash through the surface. He let go of the shark's fin and kicked up into dark, dank air.

Treading water in emptiness, Cyrus wheezed. "Tigs!" he yelled. "Dennis!"

He heard coughing. "Cy ... help. Dennis-"

Someone threw up.

Cyrus swam toward his sister's voice, but he couldn't tell if he was moving in the right direction-or moving at all. He stopped and bobbed on the surface he couldn't even see, swallowing cool lake water.

"Marco!" he yelled.

"Cyrus ... it's not ..."

She wasn't far. Cyrus splashed forward as fast as he could until he slapped something with a stroke.

"Tigs?" Cyrus felt around the body. Dennis's cape. He was still below the surface. From behind, Cyrus got his arms under Dennis's and rocked backward to get the porter's face above the water. The caped body shook, kicked Cyrus in the shin, and then threw up on his hands.

Antigone gasped beside them.

"Tigs, I'm here, I'm here," Cyrus said.

"Dennis was pulling ... me down." She coughed hard, and then gagged. "I tried, couldn't hold ... kept sinking."

"I got him," Cyrus said. "You okay? Can you help me keep him up?"

With a sharp clank and a buzzing, flickering explosion, the darkness sizzled into blinding light.

Cyrus closed his eyes against the pain, and then opened them into a squint. The blur solidified. They were bobbing in a pool. High walls were covered with white tiles, cracked and stained and occasionally missing, but glistening beneath a ceiling crowded with caged lights.

The water looked as black as liquid coal, and a large dorsal fin was carving it in slow circles.

"Mr. Douglas!" Cyrus yelled. "Where are you?"

"Over here, boy. Get out and help the cripple."

Antigone sputtered laughter. "Turn, Cy. We're right at the edge. Would suck to drown right here."

Cyrus kicked slowly while Dennis flailed his arms. "Would suck to drown anywhere," he said, spitting water.

Two yards behind him, the pool ended and a tile floor stuck out its lip a foot above the water.

Antigone swam to the wall, boosted her waist up onto the edge, hooked a knee, and rolled out.

When Cyrus reached the wall, he braced himself while Antigone grabbed Dennis's arms and Cyrus heaved the groaning porter up onto the tiles. His wet cape dripped over the edge, and his crushed bowler hat-still tied on-covered his eyes.

Cyrus flopped out of the water and looked around. The room was littered with small wooden crates and old rusted gear on collapsed shelving.

From the other side of the room, Mr. Douglas, pale and dripping, grinned at him. He was sitting with his back against the wall beside a doorway, just beneath a large metal electrical switch. A wet trail on the dirty tile showed where he'd dragged himself across the floor.

"Always hated Benjamin Sterling," the old man said. "Mr. Whispers and Secrets, we used to call him. A plotter and that's that. I won't touch his cooking."

"Who called him that?" Cyrus asked.

"My own self and all my dead brothers. He poisoned my Evelyn ten years back-I don't doubt it-and still he's cooking for the Order." He shook his head. "No-legged liar with a bit of charcoal for a heart."

Cyrus looked at the old man's sagging ribs and skeletal legs. "We need to get you some clothes. Can you stand up?"

"No, I can't stand up. Didn't you bring along my wheelchair?" Llewellyn cackled laughter and then checked his teeth. "And no need for clothes. We'll stay here for a touch, and when Benjamin Filthy Sterling has moved along, Lilly will take us back. Haven't had a swim or a bit of adventure in two ages. Feels like an old friend."

"Who's Lilly?" Antigone asked. She had rolled Dennis onto his belly.

"The last of my bulls," Llewellyn said. "The one the Keepers missed. I raised hundreds of pups in this pool right here. My sweet Lilly was from the final brood-before my legs gave. The biggest I ever bred, too. She's six meters for sure. An ancient lady now-thirty years old-but she still remembers old Llew."

"You want to go back out of here on that shark?" Antigone asked. "Dennis is half dead. I almost drowned. Isn't there another way? What's through that door?"

"Locks and more locks," Llewellyn said. "And stairs and tunnels that lead up to the Crypto wing of the zoo. This was part of it. Been locked for decades-since the Keepers lost control of the collections."

Cyrus glanced at the man's underwear and looked back at his sister. "Tigs, I'm gonna need Dennis's cape over here."

Antigone reached around Dennis and undid his cape. She threw it toward Cyrus, and the heavy, wet cloth slapped to the floor. Then she grabbed at her pockets.

"Cyrus, my Quick Water's gone."

"Already lost mine," Cyrus said. "It doesn't like real water."

"Oh, don't worry." The old man pointed at the pool. "If you dropped it in here, I'm sure Lilly will have eaten it. She's waiting around for a treat like a good little sharklet. Not that I have one for her." He turned to Cyrus. "She bolted your glowing ball right down. Can't blame her-not many twinklings in the deep water."

Cyrus walked to the edge of the pool and watched the big shark carve her circles.

"Pull me over there." Llewellyn rocked in place. "Let's see how much the old girl remembers."

While Dennis, still facedown, moaned and coughed and spat on the tile, Cyrus and Antigone tied the wet cape around Llewellyn's neck like an ap.r.o.n, and then dragged him to the edge of the pool.

Sitting with his feet in the water, the old man stretched his fist out over the surface. Lilly's circles changed. The dorsal did one loop at the far wall and then disappeared.

Llewellyn slapped the tile floor.

"Stand back," he said, and the water exploded.

Eighteen feet of shark flew out of the water and slammed onto the tile floor. A pectoral fin smacked the old man, and he tumbled toward Dennis. Cyrus and Antigone both yelled, jumping back with the heavy spray. Cyrus slipped on the wet tile and landed on his back.

Antigone kept her feet, eyes wide and heart racing. Lilly's yellow eye rolled in its socket, scanning the room.

The old man army-crawled back toward the shark. "Beautiful girl," he said, like he was talking to a puppy. "Look at you ... lovely Lillith!" The shark's gills flapped, and she swiped the pool with her tail, sending a wave of water up onto Dennis.

Moaning, dripping, Dennis Gilly finally pushed himself up onto his knees and slid back his hat.

His eyes widened and he squealed, scurrying backward into a pile of wooden crates.

Llewellyn stroked the shark's blunt head, cooing and chattering all the time. Then he made a fist and tapped her nose.

"What's in your belly, beautiful girl?" he asked. "What have you been eating to get so big?"

Lilly levered up her head, wrinkling the skin on her dark, thick back. She opened a gaping, cavernous mouth full of teeth, and then, with a noise like ten pigs belching, she regurgitated a huge load of diced fish.

"Good girl!" Llewellyn said, slapping her head. He looked over his shoulder at the shocked kids. "It's one of the first things I taught the pups. You have to monitor diet early on. Only fish for my sharks. People notice if geese and Labradors start getting pulled under."

Looking at the pile, Antigone cringed. "People notice if people start getting pulled under. What would you do if there was a foot in there?"

The old man laughed and patted the shark's rippling gills. Lilly began writhing, slapping her fins and wriggling her way back toward the water.

"There wouldn't be. I taught my little girl well. And she knows you now, too. She could smell you across the lake. She'll be a friend to you if you ever need one." He nodded at Cyrus. "Your glowing jelly will be in that pile there. Maybe the girl's, too. Dig around."

Lilly the bull shark tipped over the edge and sent another wave rushing across the tile and swirling through the pile of once-eaten fish.

A clear, gelatinous ball rolled free.

"Pick it up, Cyrus," Antigone said. "I'm not touching that gunk."

Panting in the crates, Dennis pointed at the old man. "I need my cape back."

"No," Cyrus said, glancing at Llewellyn. "No, you don't." He scooped up the Quick Water, squeezed it in half, and tossed a piece to Antigone. He dropped his piece back into his wet pocket. "Mr. Douglas, we're gonna try the doors. I like Lilly fine, but I don't want to do that again. Do you want to come?"

"No," said the old man. "I do not."

"He has to," Antigone said. "He can't go back on the shark alone. How would he get out of the water?"

"I do not have to do anything, young lady. How did I get out of the water here?" Llewellyn shrugged his shoulders free of the cape and raised his Halloween limbs. "I have arms."

"I don't want to come," said Dennis. "And I don't want to go back."

"Don't be dumb, Dennis," said Antigone. "We have to do something."

"I don't know," said Cyrus. "He could survive on Lilly's fish bits for a while."

"Cy ... I'm not even going to say anything." Antigone walked over to the metal door and banged it open. "Not locked." Reaching around inside, she found a switch. The doorway brightened with a click. "Stairs," she said. "Pick up the old man and come on."

"Don't touch me," Llewellyn said. "I'm your diving tutor, aren't I? Show some respect. Besides, even if the doors to the zoo are unlocked, you don't want to go that way. Those creatures are less than friendly."

"Yeah?" Antigone put her hands on her hips. "What about sharks? When did they become friendly?"

"Lilly came in a litter of thirty and she was the friendliest pup of them all. Always was and always will be. Never a nip from Lilly."

"Um ..." Cyrus pointed at the black pool. "What about that one?"

Llewellyn squinted at the water. A second dorsal, badly scarred, was tailing behind Lilly's figure eights.

"Well, snicker my doodle," Llewellyn said. "Lilly's found a friend." He laughed, giddy as a birthday boy. "A wild bull! And all this time, I've been thinking she's lonely. I've been sitting out on that jetty worried about my girl."

The old man slid his feet back in the water and rested his chin on his hands, watching the two dorsals swirl.

He sighed, scrunched his wrinkled face, and glanced back at the kids, dabbing his eyes. "If I had a daughter, which I don't, I imagine this is what it would be like seeing her coming down the aisle in white." He pointed at the second dorsal. "You treat her right, you hear me? I'll come in there. I will! I'll come for you."

"Right," said Cyrus. "You're a kook, and we're not going back in there."

"Suit yourselves," Llewellyn said. He took off the cape and threw it at Dennis. "We'll meet again," he said. "If you survive the zoo."