Resonance

To Danny: best and truest in all the world.

And to my girls: every day an adventure, every day a gift.

ACKNOWLEDGMENTS

First of all, a huge thank-you to the readers, bloggers, librarians, and booksellers who have supported Del's story. Bookish people are my people, and your kindness and enthusiasm means the world. Thanks for taking this journey with me.

Joanna Volpe has been in my corner from the very beginning. She has grit, heart, imagination, and intelligence in vast quantities, and I am so thankful to be working with her. I'm equally grateful to Kathleen Ortiz, Danielle Barthel, Jaida Temperly, and the rest of the team at New Leaf Literary for making this book, and my life, infinitely better.

Zareen Jaffery's brilliant insights ranged from physics to family dynamics, and she made the process of writing this book a genuine pleasure. I am so thankful for the opportunity to work with her. Thanks as well to the rest of the S&S family, who have made me feel so welcome and taken such good care of this book, especially Justin Chanda, Mekisha Telfer, Jenica Nasworthy, Brian Luster, Siena Koncsol, Lizzy Bromley, and Kristin Ostby, secret origami artist.

Writer friends are essential for brainstorming, procrastination, and whip-cracking depending on the situation, and I have the best of the bunch: the women of Chicago-North RWA, particularly Erin Brambilla, Ryann Murphy, and Melanie Bruce. I'm also grateful to farther-­flung friends: Dana Kaye, Susan Dennard, Erin Bowman, Sarah J. Maas, Veronica Roth, Lori Lee, Leigh Bardugo, and Stacey Kade, for their kindness, support, and general shenanigans.

Pamala Knight and Thomas Purnell handled inane research questions with speed and good humor. Paula Forman, Judy Bergman, Lisa
Tonkery, Lisa McKernan, and Lexie Craig dragged me out of my office and back into the real world. I thank you, and so does my family.

This book wouldn't exist without my Portland Midwest compatriots, Clara Kensie and Melonie Johnson—and especially Lynne Hartzer, who solves plot problems and supplies popcorn, often at the same time.

Hanna Martine and Loretta Nyhan are dear, wise, wonderful women, generous with their time and talent and compassion. It's a privi­lege to call you my friends.

Eliza Evans, best friend and partner in crime: I'm grateful every single day that I made that phone call. (You know the one.) Thank you for always knowing the perfect thing to say or do.

A thousand thanks to my sister, for cheering me on—and for explaining the mechanics of IV insertion eleventy billion times. And
two
thousand thanks to my parents, for believing in me and for always making room in the budget for books.

Being a writer has always been a dream of mine—but being the mom of three brave, smart, funny, talented, amazing girls is a far greater dream, and one I get to live every day. Thank you, my sweethearts, for being you.

And most of all, thank you to Danny—for his patience, his encouragement, his kindness, his humor, and his heart. For everything, forever. I love you.

Entropy's a bitch.

Fate is cruel, luck is fickle, love is strange. Entropy is all those and more. Pitiless and brutal and jagged as the rocks that break the tide.

You can clutch to your chest all the things you love most, and entropy will scatter them with a breath. It will leave you cold and alone in the middle of chaos, the eye of your own personal hurricane.

I was born to fight entropy.

I lost.

I am not done fighting.

—Journal of Delancey Sullivan

BEGIN

FIRST

MOVEMENT

CHAPTER ONE

Days until Tacet: 25

W
HEN I WAS LITTLE, MY
grandfather told me nothing was impossible. Given enough time and the right choices, anything could happen. I believed him.

Then I grew up. I stopped believing.

Turns out, he was right.

•   •   •

Walking between worlds turns you invisible. Echoes don't notice you until you touch one of them, so people are forever looking past you. You're a vague impression, more sensed than seen, a flicker in their peripheral vision.

Invisibility suited me fine. Coming here was a risk; I wasn't allowed to Walk unaccompanied, and there was always a chance an Original would spot me crossing. But some things you need to see—or hear—to believe.

I hovered like a ghost at the edge of the crowded hallway. But when Simon Lane came around the corner, dark hair falling into blue eyes, jaw square and stubborn, smile full of trouble . . .

I knew I was the one being haunted.

Pain roared through me, hungry as a wildfire. Not my Simon, though the pitch of this world was sharp and familiar. An Echo of him, and one I knew well: the shape of his hands fitted with mine; the feel of his mouth against my throat; the lazy, prowling movements that made my knees go weak. Doughnut Simon—as vibrant and magnetic as his Original—should no longer exist.

The sound of him reached me clearly, despite the distance and bodies between us. The same frequency as the rest of the Echo, but stronger, as if his volume was turned up to eleven when everyone else was a ten.

He should have been silent. A terminal Echo, one whose Original had died. A little more than a week ago, his Original had trapped himself in a world unraveling to nothingness to save me and the rest of the multiverse. His death in the cleaving should have unraveled his Echoes, robbing them of their frequency and their lives.

This Simon should have been silent, but his pitch was true as ever.

The only explanation was that
my
Simon had survived the cleaving. He'd escaped, somehow, into the vastness of the multi­verse.

Impossible.

Hope beat in my chest, the faintest of wings. I tried to smother it, but hope feeds on the impossible as surely as grief feeds on memory.

Simon's voice reached me first, a baritone resonating warmly through my bones.

One touch.

One touch, to be certain, and I would leave. He might not remember me. Echoes didn't, usually. A few minutes, or hours, or days after a Walker left a world, her impression faded from the minds of Echoes like a mirage in the desert. This Simon might forget we'd ever met. I didn't know if the thought relieved me or broke me anew.

He swaggered through the hallway, surrounded by friends, all of them in similar layers of leather and flannel and denim, Simon in the center like a sun amid planets. I readied myself, muscles tense and ears attuned. Time slowed as he drew even with me, and my feet moved of their own accord.

He turned, laughing offhandedly at some inane comment, and caught sight of me.

His eyes met mine.

He stopped laughing.

I froze. He'd seen me. He
remembered
me. Before I could react, he broke away from his friends and grabbed me. The shock of his frequency made me go limp with relief.

My Simon was alive.

This
Simon, though, was pissed.

“Del,” he growled, waving his friends along and yanking me to the side of the hall. “Where the hell have you been?”

“I'm not supposed to be here,” I said. His hand was like iron around my arm. “You're hurting me.”

He let go and I breathed him in, leather and rain.

“What do you want?” His palms slammed against the wall
on either side of me, boxing me in. “Why are you here?”

“I needed to know if you were okay.” I tore my gaze away from the silver railroad spike flashing at his wrist.

“I'm fucking awesome.” The bitterness in his laugh made me flinch. “Until now. What do you
want
?”

I curled my fingers into fists, fighting the urge to reach for him. This close, he looked the same, right down to the scar at the corner of his mouth. He wasn't mine, but he was proof the real Simon was waiting for me, somewhere in the multiverse.

He reached for his wallet and pulled out the origami star I'd given him the night we first kissed. The Key World's frequency drifted from the dark green paper, strengthening as I took it from him. “You said you weren't coming back.”

I'd broken off our relationship—which wasn't really a relationship at all, just a series of brain-melting hookups—to be with my Simon. But like every other time I'd messed around with the multiverse, my plan went sideways. The Original Simon had seen the breakup. He'd seen
everything
. Half-Walker himself, he saw through his Echoes' eyes any time they interacted with a Walker. All the times I'd kissed this Simon, the real one had experienced it as a dream; when he found out, I'd nearly lost him.

Now, maybe I could use it to find him.

“Simon.” I laced my fingers with his, star pressed between our palms. “I need you to wait for me.”

“I'm done waiting,” he snapped.

I ignored the words and focused on his eyes, a darkly gleam
ing blue. “Hang on a little bit longer. Wherever you are, whatever you're doing, keep doing it.”

“I'm right here,” he said, confusion softening his expression.

“Listen to me.
I will find you.
I'll figure it out, but you need to leave me some breadcrumbs.”

Tears gathered on my lashes, and he used his free hand to sweep them away. “Del . . .”

“I'm coming, I swear. I will find you, and we'll fix this, and we'll be good.”

“You're crazy,” he said, but his fingers stayed twined with mine.

Was I? We'd done so much damage to the multiverse, his signal disrupting world after world . . . could my message get through?

I held his gaze, searching for some flicker of understanding, some sign he'd heard me. Nothing. I'd just have to believe.

We both would.

He slid his hand along my neck, drew me closer until our foreheads touched. “Tell me how to help.”

“Listen,” I said, dizzy from his nearness. “I'm not kissing him. I'm kissing
you
.”

I touched my lips to Echo Simon's for the briefest moment—a promise more than a kiss, and my heart began to crack, a million tiny fault lines threatening to break wide open. And then, because I couldn't bear to say good-bye, I ran.

•   •   •

Losing Simon had turned the music of the multiverse muted and flat. As I raced up the stairs, reality came rushing back. I'd
Walked the Echoes since I was a kid, and no matter how changeable the ground under my feet, I'd always found a way forward. Now I had a destination: Simon, wherever he might be.

I skidded to a halt outside the library and slipped inside, heading for the stacks. Tucked amid the biographies stood the pivot I'd arrived through. The air shivered and hummed where the skin of the world had split. I reached for the rift, felt it widen as my fingers hooked along the edge.

The library doors banged open. “Del!” Simon shouted, only to be shushed by the librarian. Through a gap in the shelves I caught a glimpse of him, raking his hands through his hair in frustration. His gaze swept the room.

Time to go.

I lunged for the Key World's frequency, and the pivot closed around me, the familiar sensation of too-weighty air pressing against my skin and filling my lungs.

An instant later I was home—same library, different books, and no Simon. For the first time in weeks, his absence didn't fill me with despair.

I'd find him soon enough.

CHAPTER TWO

T
HE TRANSFORMATION FROM ANONYMOUS TO
notorious is a surprisingly quick process.

Before I'd starting dating Simon, no one in my school cared who I was or what I did. I was marking time while my teachers marked me tardy, and the rest of the student body didn't mark me at all.

These days, everyone knew who I was and what I'd done: the last girl to kiss Simon Lane, the one who'd driven him out of town.

They were right about the kissing, anyway.

The truth of Simon's disappearance was as far beyond them as he was from me, so I let them believe the whole story and kept the truth buried alongside my grief.

Truth and grief and love, three cold, furious stars that set my course and sent me searching.

The problem was, I wasn't the only one.

•   •   •

I kept my eyes down on the way to the music wing. Reminders of Simon lingered in every corner. Phantom voices, memories clinging like cobwebs, glimpses of people who had his height but not
his heart, his long legs but not his laugh. No matter how hard I looked, he wasn't here.

My footsteps reverberated down the curving hallway. As I reached for the doorknob of the music classroom, someone shoved me from behind. I went sprawling on the tile, banging my knee and slamming my elbow. My whole arm sang from the impact, my fingers going numb.

“Watch it!” I scrambled up, cradling my arm, and whirled to see who'd pushed me.

Bree Carlson. Of course. Silky hair and wide eyes and a ­honeyed voice hiding a poison tongue. Confident she was Broadway-bound and talented enough to make it happen. Simon's ex.

One of many exes, to be honest, but the only one who'd tried to win him back. She took a step forward, deliberately crowding me.

“What is your problem?” I snapped.

“You are,” she said, her voice higher-pitched than usual. “Where's Simon?”

“He moved.”

“He didn't move,” she snarled. “It's been more than a week, and nobody's heard a word from him. He won't answer any texts. He left his dog. He left his car. He left in the middle of the season without a word to his coach or his team. He would never do that. I
know
him.”

“Simon knows a lot of girls.” I shook my head with mock pity. “All of them just as well as he knows you.”

But they didn't know him. Not the way I had.

“The two of you disappear, and now you're waltzing around
like nothing's changed. Nobody would have missed you,” she added, lip curling. “But his whole life is here. Why are you back instead of him? What did you do?”

I left him.
She was right—everything Simon loved was here, and he'd given it up, and I'd let him. The guilt dragged at me more every day. I slung my bag over my shoulder and reached for the doorknob, the ever-present ache in my chest climbing into my throat.

She shoved me again, but this time I was braced for it. I swung my backpack at her shoulder, feeling it connect with a thump.

Bree shrieked and clawed, snagging a fistful of hair. Her nail raked my cheek and I swore. It felt good to fight, to finally give action to my anger. I rammed an elbow into her stomach. Hit her with my bag again. Shoved until her spine hit the cement-block wall, and shoved again for good measure.

Walkers rarely need to fight, but younger sisters do, and Bree had nothing on Addie. She blinked back tears and panted, but went still.

“Get this straight. I didn't do anything to Simon.” I stepped away. “And if you touch me again, you'll need another nose job.”

She shook back her hair, voice wavering. “Where is he?”

“I don't know.” Admitting it hurt worse than the scratches she'd left.

“Del! Bree!” Ms. Powell, the music teacher, strode toward us. Her normally cheerful face was creased with concern. “What's going on here?”

“She attacked me!” Bree said. “I was just standing here and she went crazy. She's unstable.” She raised a trembling hand, letting a few tears fall before wiping them away. Despite having a good five inches on me, she managed to make herself look small and vulnerable.

Bree played all sorts of roles in school productions. The helpless victim was another act, and any other teacher would have bought it.

Lucky for me, Ms. Powell wasn't like the other teachers. She was a Free Walker—a rebel working to undermine the Consort, our leaders. Yesterday she'd told me Simon was alive, and my Walk had proved it. Now I needed answers, and she had them.

Her expression gave nothing away. She inserted herself between us. “Do you have any witnesses?”

Bree shook her head. “But—”

Ms. Powell cut her off. “The minimum suspension for fighting is five days, I believe. For both parties.” She paused to let that sink in. “Aren't auditions for the spring musical this week?”

Bree's nostrils flared. She leaned around Ms. Powell, saying, “Everyone knows it's your fault, you violent little freak.”

“That's enough,” Ms. Powell said. “Bree, I'll see you in class. Use the rest of the lunch period to cool off.”

Bree turned on her heel and stomped away.

Ms. Powell unlocked her door, waving me in. “After you.”

Once I was inside, face-to-face with the only person who had answers, my questions wouldn't come. I sat at the battered upright piano, resting my fingers on the cool ivory keys, not playing a note.

Ms. Powell's classroom was lined with shelves of instruments and cabinets full of sheet music. The piano was tucked into the far corner, angled so she could keep an eye on the class; a door in the opposite corner led to her office. Untidy rows of desks filled the center of the room, a lectern was at the front, and she leaned against it, watching me expectantly.

“Bree started it,” I said.

“She got you pretty good.” She gestured at my stinging cheek. “You wanted to talk?”

I swallowed, unable to find the right words. Finally I blurted, “Powell Station is in Seattle.”

Traditionally, Walkers were named after big pivots in their hometowns. But it was always their first name, never their last. I hadn't thought twice about Ms. Powell the orchestra teacher. Like an Original, I'd seen what I expected, not what was real—and Ms. Powell the Free Walker had used my weakness against me.

“Seemed fitting,” she said, giving her baton an experimental flick. “A Powell at Washington High.”

“It's not your real name?”

“Real enough.” She raised her eyebrows, a mild reproof. “I'm assuming you have more important questions than my name.”

I gripped the edge of the piano bench to keep from shaking. “I saw him. One of Simon's Echoes.”

The corner of her mouth twitched. “Doughnut Simon. Cute.”

“You were right. He's not terminal.”

She inclined her head. “And?”

“How is that possible? The Consort confirmed the cleaving. Did he outrun it?”

It takes time for a world to unmake itself. When a Walker cleaves a branch, cutting the threads connecting it to the rest of the multiverse, the destruction isn't immediate. A major, complex world could take days to fully disintegrate. I'd told Simon to run, hoping I could find a way to return and save him, but it had been a wild, foolish hope, like trying to stop a tornado with your bare hands.

Ms. Powell shifted. “Not exactly. The important thing is that he's safe.”

Joy rushed in, heady and bright, and I leaped up. “Can I see him? Can we go right now?”

“It's not that simple. We need a little time.”

I thumped down again, my happiness snuffed. “We? The Free Walkers, you mean. You're the ones who got him out? How did you do it?”

“Carefully.” Before I could press for specifics, she held up her hand. “That's all I can tell you for now. You're going to have to trust me.”

“Trust you? You haven't even told me your real name. You've been watching me all year and you never said a word.” I paused. “Mr. Samson didn't want to retire, did he? You bribed him, or threatened him, or something.”

“Hardly. He retired and we took advantage of the situation.” Ms. Powell brushed at her cloud of wiry blond hair, impatient. “I wasn't sent here to watch you.”

I snorted, and she peered at me through her cat-eye glasses. The lenses were Coke-bottle thick, but now I wondered if she even needed them. If anything about her was what it appeared. She'd shown up at the beginning of the school year and fit in perfectly.

Too perfectly.

Only a Walker would be able to blend in the way she did. We were experts at hiding in plain sight.

“My assignment was to monitor Simon. You were . . . a happy coincidence. A bonus.”

I blinked. Simon? I was the one who could Walk. Simon couldn't even hear pivots. The Walkers didn't know he existed—his father had made sure of it.

Maybe his father was the key.

“Because his dad was a Free Walker?” Was. Dead for seventeen years, captured by the Consort and executed for treason. Until a month ago, Simon had no idea.

“Gilman Bradley was a good man in an impossible situation, much like his son is now. He was captured as part of a broader attack against the Free Walkers. It's taken us years to recover. It was imperative we not engage with Simon, for his own protection, but we've needed to watch him more closely as he's aged.”

“You knew about his signal flaw?”

Everything in the Key World—people, objects, oceans—resonated at the same perfectly stable frequency. As a Half Walker, Simon's signal was unusually loud, so he created more Echoes than most people. For reasons we couldn't understand,
his signal carried a flaw that was amplified and transmitted through the multiverse, affecting any world containing one of his Echoes, growing increasingly unstable over time. It's why he'd cleaved himself—to silence the damaged signal and stabilize the worlds.

And the Free Walkers had known about it. We'd thought Monty was our only option; the only person we could trust, and it had backfired horribly. The familiar anger swelled and found a fresh target.

“Why didn't you help him? Why didn't you say something?”

“We didn't realize the flaw would become such a problem; once we did, we weren't sure we could trust you. This conversation alone is a huge risk.”

The feeling was mutual. If the Consort knew I was talking to a Free Walker, they'd throw us both in an oubliette. But desperation trumps caution, especially when your hand is lousy to begin with. “You let me think he was dead!”

“Yesterday was the first time you've shown up for school since the cleaving,” she said. “Besides, we weren't going to endanger our network and our most valuable asset before we were certain you wouldn't reveal us to the Consort.”

“He's not an asset,” I said, shoving away from the piano. “He's a human being. And we both know the Consort would kill Simon the minute they laid hands on him. I'm not about to go running to Lattimer.”

“Glad to hear it,” she replied.

I folded my arms and studied her. She was too calm. She'd
known exactly what I would do when she dropped her bombshell, and she'd prepared for my reaction.

But she was right—telling me was a risk, which meant she was expecting a payoff.

“You didn't tell me because you felt sorry for me. What are you after?”

Nothing makes you more vulnerable than ignorance. Mine had allowed Monty to manipulate me, and I wasn't going to repeat the mistake. Besides, it's always easier to bluff when you know the cards you're holding.

Ms. Powell set the baton down, her eyes behind the thick glasses boring into mine.

“We want you to join the Free Walkers. Help us destroy the Consort.”

“You're joking,” I said, a too-nervous laugh bubbling up. “You can't destroy the Consort. It's suicide.”

Without the Walkers, the Key World would be destroyed. Without the Key World, the multiverse would crumble.

“Not just suicide. Armageddon. You people really are crazy.” I edged toward the door, but she moved quickly to cut me off, holding her hands out as if trying to calm a spooked animal.

“We saved Simon, didn't we?” she said. “Is that something a bunch of crazed anarchists would do?”

I paused.

“Think about all the lies the Consort has told you, Del. All the secrets they've kept. Is it such a stretch to think they lied about us, too?”

She took a step toward me and I eased away, nearly tripping over my backpack. “We're trying to save the multiverse, and Simon as well. But we need your help.”

Walkers are trained to think about consequences. Every action has a consequence; every choice makes a world. I wasn't even sure what Ms. Powell wanted me to do. But the only thing that mattered was getting back to Simon. I'd save him, then deal with the fallout.

Before I could reply, the bell rang, and we both winced at the noise. “Think about it,” Ms. Powell murmured as my classmates began trickling in.

“Missed you at lunch,” Eliot called as he set his books on the desk. I came around the side of the piano, and his mouth dropped open. “Your face!”

In my shock, I'd forgotten about Bree's scratch. I ran a finger over my stinging cheek. “Is it bleeding?”

“A little.” He grabbed a tissue from the top of the piano and handed it to me. “What happened?”

I rolled my eyes. “Bree.”

“You need to go to the nurse,” he said.

“It's nothing,” I said as Bree sidled into the classroom. I bared my teeth at her. “It won't happen again.”

She blanched as she took her seat.

Gently Eliot turned my face to inspect the marks. “It looks terrible.”

“Thanks. I'm not self-conscious about it at all.”

His hand fell to his side, his voice turning overly casual. “You never said where you went during lunch.”