Phipps reached the head of the double line, and the drum stopped. The four agents who guarded the round, two-story door to the Doomsday Vault saluted Phipps and turned to the Vault controls. Each guard knew only one sequence of instructions for opening the Vault, to ensure that no one person could open it alone. The first guard spun a large wheel that reminded Gavin of an airship helm, then spun it backward, then forward. The second guard spoke rapidly into a speaking tube. The third guard turned a series of dials set into the door. The fourth guard took a card from his pocket, punched a series of holes in it with an awl, and fed the card into a slot. A moment of silence followed. Gavin held his breath. With a dull booming sound, the great door swung outward.

Lights inside the Vault flickered to life, revealing a wide, long tunnel lined with shelves. Strange objects, some of them moving, occupied the spaces. Gavin couldn’t see into the Vault very well from his vantage point, but he didn’t need to. He pulled from his pocket a small object of his own: two glass bulbs connected by a third, like an hourglass with a slight bulge in the middle. The top bulb held water. The small middle bulb held a cube of sugar. The lower bulb held a clear green fluid. Gavin twisted a small brass lever on the side of the device, and the water in the top bulb rushed down over the sugar cube and into the absinthe in the lower bulb just as Phipps entered the Doomsday Vault. The absinthe in the lower bulb bubbled and changed to a milky green.

“What are you doing?” hissed Donaldson, the agent next to him. “Put that away!”

Gavin flipped the glass lid off the device and forced himself to drink, grimacing at the cloying taste of anise. By now, some of the others had noticed. They stared, uncertain what to do about this flagrant breach of protocol. Before they could make up their minds, a fluttering sound came from the stairwell, and a little automaton emerged into the hall, its propeller whirling madly. It held a red ball of the type Gavin had cautioned Alice not to drop in the weapons vault.

“Sorry, everyone!” Gavin shouted.

Phipps, still holding the Impossible Cube, spun in surprise just as the automaton dropped the ball on the stone floor. Pink pollen burst into the air and formed a sweet, choking cloud. The agents staggered as if drunk. Several dropped to the ground.

Gavin was already moving, the taste of absinthe still in his mouth. He sprinted toward the Doomsday Vault and caught Lieutenant Phipps as she slid to the floor. The Impossible Cube had already fallen at her feet. It glowed like a piece of broken sky.

“Wha—?” Phipps said.

“Sorry about this, Lieutenant,” he said again. “I really am.”

“Why?” Her eyelid flickered. “Why . . . Gavin?”

Gavin hung his head in guilt. Phipps had turned a disgraced cabin boy into a full-fledged agent, and now he had betrayed her.

Alice rushed down the stairs, her lips smeared green. Click and Kemp followed behind her, and the little automaton fluttered down to land on her shoulder. “We have to hurry. You said the pollen wouldn’t last more than an hour.”

“Alice . . . of course . . . ,” Phipps slurred. “You want . . . the cure . . . wreck . . . world.”

“It needs to be wrecked,” Alice said, “so it can heal. Kemp, Click—you two wait out here. If Lieutenant Phipps wakes up, hit her on the head.”

“Yes, Madam.”

Gavin snatched up the Impossible Cube. Dr. Clef had charged it, and no one had wanted to drain the charge before the ceremony. It felt springy, as if made of pine boughs. Together he and Alice hurried into the open Doomsday Vault.

The long room inside was crowded with inventions, some on shelves and some on the floor. Some were easily recognizable as dangerous: a bomb the size of a sofa; a glass vial filled with black liquid and marked DEATH; an enormous energy rifle pointed at the ceiling. Others were a mystery: a single automaton with no features; a trumpet; a thick book; five live hamsters in a cage with no food or water. Each object had a small placard in front of it with a name and year. The very first one, closest to the door, was a large iron ball with spikes. The faded placard read RICHARD W., 1829. A chill ran down Gavin’s spine.

“Incredible,” Gavin breathed. “The power in this room could destroy the world a hundred times, and we walk around above it, living normal lives.”

“Our lives are far from normal,” Alice said tersely. “We need to find the cure and get out.”

They followed the tunnel to the back, where the placards were fresher. The line of inventions stopped, though the Vault itself continued for some distance.

“The Ward means to continue collecting these dreadful things,” Alice said. “Look!”

She picked up a largish spider made of polished black metal. Several tubules ran up and down the spider’s legs. The placard read EDWINA M., 1858.

“That’s the cure?” Gavin said dubiously.

“It’s the only Edwina invention in here.” Alice snatched it up. “We don’t have time for doubt. Let’s go!”

They hurried back to the entrance of the Vault, each of them carrying a doomsday device. Gavin’s heart beat fast, and his hands tightened around the Impossible Cube. Every move he made changed history, altered millions of lives, and that responsibility frightened him even more than the possibility of being caught and hanged. Maybe this was how Queen Victoria and President Pierce felt all the time.

“Shall I carry that for Madam?” Kemp asked.

“Thank you, no,” Alice said, clutching the spider to her chest. “Click! Hurry!”

The five of them, counting the little automaton that still sat on Alice’s shoulder, dashed past the sleeping agents down the hall where the clockworkers were locked in their laboratories, and found Edwina’s door. Gavin stared at the heavy wood for a moment, surprised at the amount of loathing he felt. Behind that door was the woman who had kidnapped him and infected him with the clockwork plague. He’d been trying not to think about that, to concentrate on the mission; however, now faced with setting her free, he felt disgust and hatred boiling black inside him.

“What are you waiting for?” Alice hissed. “Hurry!”

Gavin clenched his teeth. “She’s a monster.”

“Oh, Gavin!” Alice put a hand on his arm. “Gavin, I know it’s hard.”

“You have no idea, Alice. To her, I’m a windup music box, an automaton who’ll obey orders. She trapped me in this horrible, filthy city, and now she’s dragged me underground and is forcing me to set her free.”

Kemp made a coughing sound.

“I know, Gavin,” Alice said. “What she did is unforgivable. But you can move on. You’re bright and merry and you soar. Your hatred won’t change her, or what she did. Don’t give her the power to chain you down and ruin you.”

Gavin faced her. Every muscle in his back ached, and the cube grew heavy. His throat thickened. “I don’t know what to do, Alice. I hate this world. I hate the people in it. A man named Madoc Blue tried to do unspeakable things to me and I killed him. His blood was still on my hands when the first mate ripped my back to shreds. And then the Red Velvet Lady summoned me like a sorceress with a spell and locked me in her round tower so I would do her bidding. She’s the figurehead of all the horrible things that have happened to me. To my world. I’ve fallen so far, Alice, and I just want to fly again, be free of all these horrible people.”

“Free from me, Gavin?” Her arms went around him, and she kissed him. The warmth of her body went through him, and he closed his eyes, soaking in her presence. Thank God he wasn’t contagious yet.

“Can you do this?” she asked when they parted. “Not for me. For you. And for the world.”

Gavin bit his lip and nodded. Then he put his hand on the Impossible Cube, took a deep breath, and sang one note. The crystal D-sharp thrummed through him, built in intensity, rushed upward, and roared from his throat. The energy blew the door inward so hard, it cracked in two and the pieces smashed against the opposite wall. Gavin continued to sing. The Impossible Cube glowed blue in his hands. He was aware of Alice shouting at him, but he couldn’t stop. Silky anger and disgust poured out of him, slid from his throat in an orgasmic black stream. The badness felt so good, and he felt so bad that it felt good. He struggled against it, then gave in. His body shuddered with the pleasure of it. The cube glowed brighter, and his anger thundered through the underworld until the stones began to crack, and still there was more and more and more. Edwina shouted something at him, and he snapped his head toward her. She dived aside, and the power of his voice shattered the stones behind her. More and more fury tore from him. A hand grasped his shoulder, and he rounded with righteousness.

It was Alice. Her face held no trace of fear, only wonder and concern. Alice, who had also come from the hell that was London. He felt her love, both quiet and fierce, and the music buried within his anger answered it. Before the terrible note could touch her, he tightened his throat and changed it.

The new note rang white and clean as a bell that had only just cooled in the mold and still remembered what it was to be hot and pure. It swept every color of sound along the cracked stone corridors and poured over the sleeping agents, who smiled in their drugged sleep. It rushed over Alice and sheathed her in light, lifting her gently off the floor while sparks flickered about her like snowflakes. The little whirligig on her shoulder clung to its perch.

Gavin’s note faded. Alice drifted to the floor, her eyes wide. The glow faded from the Impossible Cube, and Gavin dropped it. As the cube tumbled toward the floor, it changed colors—blue to green to yellow to orange to red. The moment it touched the flagstones, red energy exploded in all directions with a bone-jarring whump and a blast of warm air that stirred hair and clothes. The cube was gone.

“Good Lord,” said Edwina.

Alice touched Gavin’s face. “Are you all right?”

He put his palm on her hand, unable to do anything but nod. Then all the strength left him. His knees buckled, and only Kemp’s chilly hands stopped him from dropping to the floor.

“Gavin!” Alice grabbed for him as well.

“I’m . . . all right.” His voice was scratchy, and he managed to regain his feet. “Thank you, Alice. For bringing me out of that.”

She wrapped her arms hard around him, her face wet with tears. “You’re thanking me? God, Gavin. I love you always.”

“I love you always.”

“Heavens, I am good.” Edwina emerged from the workroom carrying a spider with a large clock built into its belly. “Except for this little toy. Do you know they wouldn’t give me the parts I needed to complete—ah! Just the thing.”

She set the spider down and plucked the whirligig automaton from Alice’s shoulder. It squeaked in surprise, and before Alice or Gavin could respond, Edwina tore open its access hatch and yanked out several bits of machinery. The little automaton quivered and went still. Gavin stared in horror.

“Edwina!” Alice cried. “What—?”

“Shush, dear. Auntie’s working.” With dazzlingly fast movements, she worked the machine parts—memory wheels, Gavin now remembered—into the clock spider’s insides and closed it up. Then she unceremoniously kicked the thing back into her cell and swept the bits of the whirligig aside with her foot. The entire affair took only a few seconds.

“Ready now, darlings!”

“What was that for?” Alice demanded.

“My final project. You wouldn’t expect me to leave it uncompleted, would you?”

“But—never mind. We have to get out of here. The noise will bring dozens of people down. Do you have the other cure?”

“I do,” Edwina said. “Let’s—oh dear.”

Some of Gavin’s strength had returned, and he straightened enough to glance around. The other doors in the hallway had also been destroyed, flattened by Gavin’s voice. Startled faces, male and female, young and old, were peeping into the corridor. Dr. Clef waved to Gavin.

“We should leave now,” Edwina said. “In fact, we should run.”

They sprinted up the stairs. At the top, they met a group of workers, none of them agents.

“What’s going on?” someone shouted.

“There was an explosion in the clockworker laboratories,” Alice said. “People need help! Hurry!”

“Halt right there!” barked a new voice. Lieutenant Phipps strode purposefully, if a bit unsteadily, around the lower turn in the spiral staircase. “It’s a trick. They’ve incapacitated all our agents and broken into the Doomsday Vault.”

Fear rushed down Gavin’s spine. He glanced at the dozen-odd workers, then at Phipps. Her face was pale and grim.

“Do you think this is the first time a cure has been found and repressed?” Phipps said quietly. “You walked right past three others in the Doomsday Vault. I won’t let you release any of them.”

“I never understood you, Susan,” Edwina said. “Even in school, you contradicted yourself. You push the Hats-On Committee into sedition, but balk at this?”

“I won’t commit treason,” Phipps said. She was bracing herself against the wall for support.

“I left you a present in my cell,” Edwina told her. “My final project. In fact—”

“You have ten minutes to evacuate,” boomed Edwina’s voice from below. Gavin’s blood ran cold. It was exactly the voice he’d heard in that terrible tower all those months ago.

“Good God,” Alice gasped. “The clock spider.”

“You can arrest us,” Edwina said, “or you can get all those unconscious agents to safety. You can’t do both.”

“For the good of the Crown,” Phipps replied hoarsely, “I’ll make the sacrifice.”

“But will they?” Edwina cocked a thumb at the workers.

“I couldn’t have said it better myself,” Edwina said.

There was a moment’s hesitation. Then most of the workers swarmed around the group and out of sight down the stairs to help the agents. The remainder fled outright, leaving Alice, Gavin, Edwina, Kemp, and Click alone with Susan Phipps.

“Five against one, if you count the cat,” Edwina said. “And you’re still groggy. You can fight and lose, or you can run downstairs and save some lives.”

Phipps stared at them for a hard moment. Her eyes met Gavin’s, and the disappointment in her gaze nearly pushed him through the floor. Then Susan Phipps turned and marched down the steps.

Outside, they ran toward the barn with Click leading the way. Kemp and Gavin slid the huge doors open while Alice, Edwina, and Click rushed up the gangplank onto the little airship. When Alice arrived, more than a dozen little automatons poured out of a hatchway and surrounded Alice like a cloud of metal fairies. They squeaked with joy.

“And I’m glad to see you,” she said, “but we have no time. Cast off!”

The whirligigs and spiders scampered to obey while Edwina glanced around long enough for her plague-enhanced mind to figure out how everything worked. She cranked the generator, which coughed to life in a cloud of paraffin smoke, and pale blue energy crawled up to the envelope, where it swirled and swooped in a fine glowing pattern beneath the skin. The light revealed words painted along the gunwale. Alice read them aloud as Gavin ran up the gangplank with Kemp close behind.

“The Lady of Liberty,” Alice said with tears in her voice. “Oh, Gavin!”

Gavin grinned and flipped switches. The propellers buzzed to life while Kemp reached for the gangplank.

“Wait for me! Wait!” Gabriel Stark, known as Dr. Clef, puffed up the plank and onto the ship. He was carrying a large lumpy sack. “Du Lieber. How could you leave me behind to explode? And where is my Impossible Cube?”

“Er,” Alice said. “I’m not sure how to—”

“Oh—you have a clockwork cat. That is very nice. I will forgive you if I may pet the cat.”

“Be my guest,” said Edwina.

The airship, meanwhile, moved, gliding gracefully out the wide doors into the open air.

“It flies! Gavin. It flies!” Alice clapped her hands with joy, and Gavin’s grin widened into exultation.

“She flies,” he said.

“So this is what for you wanted all my alloy,” Dr. Clef exclaimed. “Never would I have thought of this application. Very intelligent.”

“You have four minutes to evacuate.” Edwina’s voice was clear, even outside. People streamed from the house like ants from a hill.

“Why don’t they just take the bomb outside?” Alice asked.

“They can’t, darling,” Edwina told her. “The spider grabs the floor, you see, and it’s too complex for anyone but a plague genius to deactivate, and then only with days of study.”

The airship coasted past the chaos a bare six feet above the ground. No one seemed to notice them—everyone was busy dragging unconscious agents out of the house.

“You intended to destroy the Ward from the very start, didn’t you?” Alice said tightly to Edwina.

“Well, obviously. Look what they’ve done to us. To you. That device will make the one at my country house look like a mousetrap, so let’s move along, please.”

“I don’t see Simon or Glenda or Lieutenant Phipps,” Gavin said. He felt sick. “They won’t make it out.”

“They’d have you hanged, given the chance,” Edwina said.

Gavin’s fingers whitened on the helm. The propellers beat their inexorable rhythm as the ship glided on. An agent Gavin didn’t recognize stumbled out the door, helped by a workman, then dropped to his knees on the front steps. He thought about Susan Phipps and the others downstairs, moving through air like molasses while Edwina’s voice counted down to doomsday.

Abruptly he yanked the cord from the generator. The dim blue light of the lattice went out, and the airship fell to the ground with a massive thud, though she retained enough buoyancy to avoid a damaging crash. Everyone rocked on his feet. Dr. Clef tipped over with a squawk.

“What are you doing?” Edwina shouted.

Gavin was already dropping over the side. “I have to do something. I have to help.”

“I’m coming with you.” Alice jumped after him, and Gavin helped her land. Together, they ran inside the house.