Steadying her courage, Petra rushed to meet it—and tripped over the hem of her nightgown.

She fell, landing on her side. The Marvel in her pocket burst, and she was engulfed in ooze.

Petra surged to her feet, spitting out frog spawn. She slipped, then caught her balance again and wiped mud out of her eyes. Slime covered the corridor. Her friends had been standing still at the time of the blast and had kept their balance, grimacing as the goo lapped their ankles. Petra could see Astrophil, who had fallen from her head, picking his way through frog spawn toward the safety of a clean wall.

The creature was on its back, floundering in the slime.

Petra stalked—as best as one can stalk through slime—toward the monster. With a single movement, it propped all ten arms against the floor and pushed itself upright. Petra let her anger burn, and funneled its energy into her magic. “I”—she chopped off an arm—“should not”—she chopped off another—“have to fight”—and another—“in a nightgown!”

Blood spurted from the creature’s torso as three arms fell to the floor, but the many mouths just laughed. One arm dropped a dagger and pulled a flask from its belt. It brought the flask to one of the mouths on its face and drank.

Three new arms sprouted out of its chest.

“Petra, get back!” Lucas shouted.

Petra, who saw the Marvel in his hand, slipped and skidded out of the way.

Lucas threw. The Marvel with the snake coiled inside smashed at the creature’s feet. It was a perfect throw. Snakes writhed up the monster’s body.

But the mouths grinned. They opened wide and chomped down on the snakes. There was a slurping sound, and the snakes were sucked into the mouths as if they had been noodles.

“Mmm,” the mouths said. “Yummy.”

Petra closed her eyes. She usually built walls around her mind-magic, but now she let it trickle in, gush, and fill her. She looked at the creature, and seemed to see each twitching move those ten arms would make. She thought she knew what to do.

She found her balance. She ran, skating along the slime as if it were ice. She ducked under the swinging arms and snatched the flask from the creature’s belt.

It howled and tried to swipe the flask back. She chopped off an arm. It fell, and no arm grew back in its place. Petra stuffed the flask into her wet pocket.

The monster drove several daggers toward her. Petra twisted aside and tried to stab its neck. An arm blocked her. When her rapier point sank into the arm’s skin, Petra tugged, and that arm thumped to the floor.

The mouths were screaming now, their voices high and low, shrill and booming. The chaos of sound distracted Petra. An arm swatted her to the ground and her body skidded. The slime wheeled her away from the monster, taking her out of danger for a moment—but only a moment.

The monster was steady on its feet. It strode toward her as she struggled to stand. A dagger stabbed toward her stomach, and another toward her eye. Petra rolled in the slime, and in one breathless instant she saw a clear path through all the wild arms. The space between the arms was almost like a tunnel, and Petra thrust her rapier through it to pierce the monster’s throat. She drove her blade home.

The mouths roared and howled, and Petra thought she would go deaf from the sound. Then the screams died, and silence filled the corridor.

Lucas helped Petra to her feet. “Fiala Broshek?” He nodded toward the end of the corridor.

“Fiala Broshek,” Petra agreed. She snatched one of the creature’s fallen daggers, and the friends slipped as quickly as they could over the slime, down the hall.

The corridor dead-ended, and there was a gorgeous, angel-faced woman struggling to open a small metal door in the wall. It vaguely reminded Petra of doors she had seen on the Pacolet.

Fiala Broshek froze, and glanced over her shoulder at Petra, whose sword was visible with blood. “Stay back! You’d better stay back, or I’ll…”

Yet Petra suddenly knew, as surely as she knew her own name, that Fiala Broshek’s threats were empty. Fear had made the woman’s hands clumsy with a door she must open every day. She was defenseless. She had no weapons. Her weapons had been her monsters.

Petra sheathed her rapier. She gripped her dagger with one hand, and with the other she snatched the gray, misty Marvel from Lucas. She hoped it would do what she thought. She smashed it on the ground. Smoke curled from the shards and spread through the room.

Her friends were shouting at her, but Petra didn’t listen. She rushed through the fog, dagger in hand. It felt like she was swimming. She couldn’t see. But, even blind, she could sense Fiala Broshek. She could tell that the woman had frozen, then fumbled again with the door, trying to open something she couldn’t see.

Petra slipped up behind Fiala and held the dagger to her throat.

“You changed my father into a Gray Man.” Petra’s voice was harsh. “I want you to change him back. Do it, or I will kill you. I will.”

“I would rather die!”

The mist began to clear. With her free hand, Petra pulled the slime-covered flask from her pocket and shoved it in front of Fiala’s face. “If you don’t cure my father,” Petra said, “I will pour this down your throat.”

There was a silence. Petra saw her friends’ faces, and wondered if their horror reflected what they saw in Fiala’s eyes.

“You are so pretty.” Petra pressed her knife until she felt the edge just barely part the skin. “How would you look with ten arms, and hundreds of mouths? How does this stuff work, anyway? Does one sip grow one arm? If you drink the whole bottle, what happens then?”

Fiala croaked, “Let’s talk.”

Petra’s arm sagged in relief, and her bare wrist touched the metal door. With a sharp gasp, Petra brought the dagger back to Fiala’s throat before the woman could wriggle free. That brief brush of skin against metal had told Petra something. She remembered the strange metal object she’d seen below the water by the pier. She remembered how frantically Fiala had tried to open the door, as if what lay beyond it was desperately important.

“That is the Tank!” Petra told her friends. “We’ve seen nothing that looks like a laboratory, have we? With brass bowls and brassica fires and alembics and weird ingredients. It must be here, behind this door.”

“Clever, clever,” Fiala spat.

Tomik stepped forward and, after careful consideration of the mechanism, opened the door. They saw a metal chamber lit by a green glow. Petra pushed Fiala inside, keeping the knife steady. Her friends filed in behind her.

The chamber was lined by tables littered with metal instruments, glass tubes, and the splayed bodies of cut-open animals. A single pink rose graced a beaker, and Petra wondered if it had been a gift or was destined for a potion. Two small doors on either end of the room seemed to lead to other chambers, and odd-looking buttons studded the walls. A glass porthole was dark with the water of the Vltava River.

Tomik slammed the small door shut and spun a knob that locked it. He looked at Fiala. “We need some rope.”

“Rip the hem of my nightgown.” Petra told Zora. “Please.”

After Zora had ripped away enough strips of fabric for Tomik to bind Fiala’s hands and feet and strap her to a chair, Petra relaxed the arm that held the dagger. “Now,” she said to Fiala, “it’s time to talk.”

“Hey,” said Lucas, “what do you think these do?” He was looking at the buttons on the wall, and his finger hovered over a red one.

“Don’t touch that button!” Fiala shouted.

But Lucas already had.

38

Underwater

THE METAL WALLS shuddered and groaned as the chamber filled with a pumping sound. The room seemed to slide and veer. Petra had no clue where the Tank was going, but it was definitely moving.

“You’re going to kill us all,” Fiala told Lucas matter-of-factly.

“What did that button do?” Petra demanded.

“You unmoored the Tank.”

“What do you mean?”

“To ‘moor’ means to anchor a ship or fasten it to a pier,” said Astrophil. “So I assume that this thing is a boat, and that we have become, well … unanchored and unfastened. I believe we have left Lady’s Lace Pier.”

The Tank chug chug chugged, and picked up speed.

“Where, exactly, are we going?” asked Tomik.

Fiala shrugged as best as she was able with her arms bound by slime-covered strips of Petra’s nightgown. “Somewhere through the river. We’re underwater, in case you seed-brains haven’t figured that out. We’re going to crash into something—a pier, or maybe Kampa Island.” Her voice smoothed into honey. “I think you should untie me.” The Tank vibrated and hummed. “I know how to sail this ship.”

“Bad idea,” said Petra.

“You’re the one willing to die,” Zora told Fiala. “You said so. You’re only afraid of being turned into a monster. You wouldn’t think twice about steering us into an island. You’d blow us up.”

“Maybe,” Fiala said, “or maybe I was just being dramatic. Or maybe I was buying time until I had the opportunity to crack open your skulls and see what’s inside. I may be many things, Petra Kronos, but I am far from stupid. Why should I believe your threat to kill me? If you truly want your doddering father back, you cannot kill me. Unbind me, and I will steer us to safety.”

“You’d steer us right to Rodolfo,” said Petra.

The Tank made a grinding noise, like it was dragging itself across the bottom of the riverbed.

“I think,” Fiala said sweetly, “that you have no choice.”

“Yes, we do,” said Petra. “We can figure out how to sail it ourselves.”

Fiala giggled.

“Maybe we should push another button and see what happens,” said Zora.

Tears of laughter streamed down Fiala’s ivory face. The grinding noise of the Tank worsened, and the floor began to shake.

Astrophil said, “Zora, I am not sure that is the best idea—”

But Zora had already pushed a purple button close to her. The ceiling sprayed water.

Petra sprang across the room and slapped her hand against the wall, pressing the button again. The water stopped. Fiala kept laughing. “Zora, Lucas, you watch her,” said Petra. She pointed at the two doors on either side of the long chamber. “The rest of us are going to see where these lead.”

Petra and Astrophil took one end, and Tomik another. “It’s a bedchamber,” shouted Tomik from his end of the Tank. Petra, with Astrophil peering anxiously from her shoulder, opened her door. “Tomik, come here!”

It was a small, round room barely large enough for two people. Two chairs covered with slipcases of pink ostrich feathers faced a table of dials and a big wheel. Beyond that was a curved glass panel that took up almost the entire room. The window was black, just as the portal had been in the laboratory.

Tomik shouldered through the narrow doorway, and he and Petra each took a pink seat.

“I don’t care how thick the metal hull of this ship is,” said Tomik. “If we keep dragging along the riverbed, the rocks will tear it apart. One of these dials has to make the Tank rise.”

“Please,” said Astrophil, “can we forgo the trial and error process that has thus far brought us close to a watery grave?”

“Your fear is making you hard to understand,” Petra muttered.

“Stop pushing buttons when you have no idea what they do,” said Astrophil. “And I am not afraid.”

Petra set her dagger on the metal table and pressed the heel of her hand against her eyes. A sickening headache was starting to build, and Petra became aware of how much magical energy she’d already spent that day. She had poured almost every physical resource she had into her magic, and felt as if she hadn’t slept or eaten in a long time.

The scraping sound of the Tank turned into a screech.

Petra gritted her teeth. She would ask the metal a few questions. Dee had taught her how to do this, long ago, and she could do it now. She ran a palm over the metal table with its knobs and buttons, and begged, Which way is up?

Her fingers seized a dial and twisted it.

The Tank rocketed upward. They were rising so fast and straight that Petra felt like her brain had slammed against the roof of her skull. She and Tomik held tight to the pink ostrich chairs, and Astrophil gripped her ear. The black water outside the window in front of them dropped away. Thin, clear water now sheeted down over the window, and Petra could see city lights flickering through it. The water slowed and ribboned, and there was Karlov Bridge, shining with green brassica lamps. Its statues looked as if they were peering down at the river, at this strange metal ship that cruised below.

“Someone might see us,” said Tomik. “By now Rodolfo—or his captain of the guard—might know about the attack on the factory, and if the Tank is spotted on the river’s surface…”

Petra dialed the knob back—slowly, this time. The ship sank underwater, and the window went black again.

“This ship is obviously designed to stay hidden underwater,” said Astrophil, “and one could not possibly sail it through the dark. There must be lights of some kind.”

Petra’s fingers fluttered over the dials, asking, What is your history? What were you designed to do? She pushed a button. Funnels of light shot into the dark water, and she could see something through the murk. Something gray and large, like a building with huge arches cut into it. “Is that…?”

“The bridge!” shouted Tomik. “It’s the foundations of Karlov Bridge!”