My mother selected her wings as early morning light reached through our balcony shutters. She moved between the shadows, calm and deliberate, while downtower neighbors slept behind their barricades. She pushed her arms into the woven harness. Turned her back to me so that I could cinch the straps tight against her shoulders.

When two bone horns sounded low and loud from Mondarath, the tower nearest ours, she stiffened. I paused as well, trying to see through the shutters' holes. She urged me on while she trained her eyes on the sky.

"No time to hesitate, Kirit," she said. She meant no time to be afraid.

On a morning like this, fear was a blue sky emptied of birds. It was the smell of cooking trapped in closed towers, of smoke looking for ways out. It was an ache in the back of the eyes from searching the distance, and a weight in the stomach as old as our city.

Today Ezarit Densira would fly into that empty sky -- first to the east, then southwest.

I grabbed the buckle on her left shoulder, then put the full weight of my body into securing the strap. She grunted softly in approval.

"Turn a little, so I can see the buckles better," I said. She took two steps sideways. I could see through the shutters while I worked.

Across a gap of sky, Mondarath's guards braved the morning. Their wings edged with glass and locked for fighting, they leapt from the tower. One shouted and pointed.

A predator moved there, nearly invisible -- a shimmer among exploding gardens. Nets momentarily wrapped two thick, skycolored tentacles. The skymouth shook free and disappeared. Wails built in its wake. Mondarath was under attack.

The guards dove to meet it, the sun dazzling their wings. The air roiled and sheared. Pieces of brown rope netting and red banners fell to the clouds far below. The guards drew their bows and gave chase, trying to kill what they could not see.

"Oh, Mondarath," Ezarit whispered. "They never mind the signs."

The besieged tower rose almost as tall as ours, sun-bleached white against the blue morning. Since Lith fell, Mondarath marked the city's northern edge. Beyond its tiers, sky stretched uninterrupted to the horizon.

A squall broke hard against the tower, threatening a loose shutter. Then the balcony's planters toppled and the circling guards scattered. One guard, the slowest, jerked to a halt in the air and flew, impossibly, backwards. His leg yanked high, flipping his body as it went, until he hung upside down in the air. He flailed for his quiver, spilling arrows, as the sky opened below him, red and wet and filled with glass teeth. The air blurred as slick, invisible limbs tore away his brown silk wings, then lowered what the monster wanted into its mouth.

By the time his scream reached us, the guard had disappeared from the sky.

My own mouth went dry as dust.

How to help them? My first duty was to my tower, Densira. To the Laws. But what if we were under attack? My mother in peril? What if no one would help then? My heart hammered questions. What would it be like to open our shutters, leap into the sky, and join this fight? To go against Laws?

"Kirit! Turn away." Ezarit yanked my hand from the shutters. She stood beside me and sang the Law, Fortify:

Tower by tower, secure yourselves, Except in city's dire need.

She had added the second half of the Law to remind me why she flew today. Dire need.

She'd fought for the right to help the city beyond her own tower, her own quadrant. Someday, I would do the same.

Until then, there was need here too. I could not turn away.

The guards circled Mondarath, less one man. The air cleared. The horns stopped for now, but the three nearest towers -- Wirra, Densira, and Viit -- kept their occupied tiers sealed.

Ezarit's hand gripped the latch for our own shutters. "Come on," she whispered. I hurried to tighten the straps at her right shoulder, though I knew she didn't mean me. Her escort was delayed.

She would still fly today.

Six towers in the southeast stricken with a coughing illness needed medicines from the north and west. Ezarit had to trade for the last ingredients and make the delivery before Allmoons, or many more would die.

The buckling done, she reached for her panniers and handed them to me.

Elna, my mother's friend from downtower, bustled in the kitchen, making tea. After the first migration warnings, Mother had asked her to come uptower, for safety's sake -- both Elna's and mine, though I no longer needed minding.

Elna's son, Nat, had surprised us by helping her climb the fiber ladders that stretched from the top of the tower to the last occupied tier. Elna was pale and huffing as she finally cleared the balcony. When she came inside, I saw why Nat had come. Elna's left eye had a cloud in it -- a skyblindness.

"We have better shutters," Ezarit had said. "And are farther from the clouds. Staying higher will be safer for them."

A mouth could appear anywhere, but she was right. Higher was safer, and on Densira, we were now highest of all.

At the far side of our quarters, Nat kept an eye on the open sky. He'd pulled his sleeping mat from behind a screen and knelt, peering between shutters, using my scope. When I finished helping my mother, I would take over that duty.

I began to strap Ezarit's panniers around her hips. The baskets on their gimbaled supports would roll with her, no matter how the wind shifted.

"You don't have to go," I said as I knelt at her side. I knew what her reply would be. I said my part anyway. We had a ritual. Skymouths and klaxons or not.

"I will be well escorted." Her voice was steady. "The west doesn't care for the north's troubles, or the south's. They want their tea and their silks for Allmoons and will trade their honey to the highest bidder. I can't stand by while the south suffers, not when I've worked so hard to negotiate the cure."

It was more than that, I knew.

She tested the weight of a pannier. The silk rustled, and the smell of dried tea filled the room. She'd stripped the bags of their decorative beads. Her cloak and her dark braids hung unadorned. She lacked the sparkle that trader Ezarit Densira was known for.

Another horn sounded, past Wirra, to the west.

"See?" She turned to me. Took my hand, which was nearly the same size as hers. "The skymouths take the east. I fly west. I will return before Allmoons, in time for your wingtest."

Elna, her face pale as a moon, crossed the room. She carried a bowl of steaming tea to my mother. "For your strength today, Risen," she said, bowing carefully in the traditional greeting of lowtower to high.

My mother accepted the tea and the greeting with a smile. She'd raised her family to the top of Densira through her daring trades. She had earned the greeting. It wasn't always so, when she and Elna were young downtower mothers. But now Ezarit was famous for her skills, both bartering and flying. She'd even petitioned the Spire successfully once. In return, we had the luxury of quarters to ourselves, but that only lasted as long as she kept the trade flowing.

As long as she could avoid the skymouths today.

Once I passed my wingtest, I could become her apprentice. I would fly by her side, and we'd fight the dangers of the city together. I would learn to negotiate as she did. I'd fly in times of dire need while others hid behind their shutters.

"The escort is coming," Nat announced. He stood; he was much taller than me now. His black hair curled wildly around his head, and his brown eyes squinted through the scope once more.

Ezarit walked across the room, her silk-wrapped feet swishing over the solid bone floor. She put her hand on Nat's shoulder and looked out. Over her shoulders, between the point of her furled wings and through the shutters, I saw a flight of guards circle Mondarath, searching out more predators. They yelled and blew handheld horns, trying to scare skymouths away with noise and their arrows. That rarely worked, but they had to try.

Closer to us, a green-winged guard soared between the towers, an arrow nocked, eyes searching the sky. The guards atop Densira called out a greeting to him as he landed on our balcony.

I retightened one of Ezarit's straps, jostling her tea. She looked at me, eyebrows raised.

"Elna doesn't need to watch me," I finally said. "I'm fine by myself. I'll check in with the aunts. Keep the balcony shuttered."

She reached into her pannier and handed me a stone fruit. Her gold eyes softened with worry. "Soon." The fruit felt cold in my hand. "I need to know you are all safe. I can't fly without knowing. You'll be free to choose your path soon enough."

After the wingtest. Until then, I was a dependent, bound by her rules, not just tower strictures and city Laws.

"Let me come out to watch you go, then. I'll use the scope. I won't fly."

She frowned, but we were bartering now. Her favorite type of conversation.

"Not outside. You can use the scope inside. When I return, we'll fly some of my route around the city, as practice." She saw my frustration. "Promise me you'll keep inside? No visiting? No sending whipperlings? We cannot lose another bird."

"For how long?" A mistake. My question broke at the end with the kind of whine that hadn't slipped out in years. My advantage dissipated like smoke.

Nat, on Ezarit's other side, pretended he wasn't listening. He knew me too well. That made it worse.

"They will go when they go." She winced as sounds of Mondarath's mourning wafted through the shutters. Peering out again, she searched for the rest of her escort. "Listen for the horns. If Mondarath sounds again, or if Viit goes, stay away from the balconies."

She looked over her shoulder at me until I nodded, and Nat too.

She smiled at him, then turned and wrapped her arms around me. "That's my girl."

I would have closed my eyes and rested my head against the warmth of her chest if I'd thought there was time. Ezarit was like a small bird, always rushing. I took a breath, and she pulled away, back to the sky. Another guard joined the first on the balcony, wearing faded yellow wings.

I checked Ezarit's wings once more. The fine seams. The sturdy battens. They'd worn in well: no fraying, despite the hours she'd flown in them. She'd traded five bolts of raw silk from Naza tower to the Viit wingmaker for these, and another three for mine. Expensive but worth it. The wingmaker was the best in the north. Even Singers said so.

Furled, her wings were a tea-colored brown, but a stylized kestrel hid within the folds. The wingmaker had used tea and vegetable dyes -- whatever he could get -- to make the rippling sepia pattern.

My own new wings leaned against the central wall by our sleeping area, still wrapped. Waiting for the skies to clear. My fingers itched to pull the straps over my shoulders and unfurl the whorls of yellow and green.

Ezarit cloaked herself in tea-colored quilted silks to protect against the chill winds. They tied over her shoulders, around her trim waist and at her thighs and ankles. She spat on her lenses, her dearest treasure, and rubbed them clean. Then she let them hang around her neck. Her tawny cheeks were flushed, her eyes bright, and she looked, now that she was determined to go, younger and lighter than yesterday. She was beautiful when she was ready to fly.

"It won't be long," she said. "Last migration through the northwest quadrant lasted one day."

Our quadrant had been spared for my seventeen years. Many in the city would say our luck had held far too long while others suffered. Still, my father had left to make a trade during a migration and did not return. Ezarit took his trade routes as soon as I was old enough to leave with Elna.

"How can you be sure?" I asked.

Elna patted my shoulder, and I jumped. "All will be well, Kirit. Your mother helps the city."

"And," Ezarit said, "if I am successful, we will have more good fortune to celebrate."

I saw the gleam in her eye. She thought of the towers in the west, the wealthier quadrants. Densira had scorned us as unlucky after my father disappeared, family and neighbors both. The aunts scorned her no longer, as they enjoyed the benefits of her success. Even last night, neighbors had badgered Ezarit to carry trade parcels for them to the west. She'd agreed, showing respect for family and tower. Now she smiled. "Perhaps we won't be Ezarit and Kirit Densira for long."

A third guard clattered to a landing on the balcony, and Ezarit signaled she was ready. The tower marks on the guards' wings were from Naza. Out of the migration path; known for good hunters with sharp eyes. No wonder Nat stared at them as if he would trade places in a heartbeat.

As Ezarit's words sank in, he frowned. "What's wrong with Densira?"

"Nothing's wrong with Densira," Elna said, reaching around Ezarit to ruffle Nat's hair. She turned her eyes to the balcony, squinting. "Especially since Ezarit has made this blessed tower two tiers higher."

Nat sniffed, loudly. "This tier's pretty nice, even if it reeks of brand-new."

My face grew warm. The tier did smell of newly grown bone. The central core was still damp to the touch.

Still, I held my chin high and moved to my mother's side.

Not that long ago, Nat and I had been inseparable. Practically wing-siblings. Elna was my second mother. My mother, Nat's hero. We'd taken first flights together. Practiced rolls and glides. Sung together, memorizing the towers, all the Laws. Since our move, I'd seen him practicing with other flightmates. Dojha with her superb dives. Sidra, who had the perfect voice for Laws and already wore glorious, brand-new wings. Whose father, the tower councilman, had called my mother a liar more than once after we moved uptower, above their tier.

I swallowed hard. Nat, Elna, and I would be together in my still-new home until Ezarit returned. Like old times, almost.

In the air beyond the balcony, a fourth figure appeared. He glided a waiting circle. Wings shimmered dove gray. Bands of blue at the tips. A Singer.

A moment of the old childhood fear struck me, and I saw Nat pale as well. Singers sometimes took young tower children to the Spire. It was a great honor. But the children who went didn't return until they were grown. And when they came back, it was as gray-robed strangers, scarred and tattooed and sworn to protect the city.

The guards seemed to relax. The green-winged guard nudged his nearest companion, "Heard tell no Singer's ever been attacked by a skymouth." The other guards murmured agreement. One cracked his knuckles. Our Magister for flight and Laws had said the same thing. No one ever said whether those who flew with Singers had the same luck, but the guards seemed to think so.

I hoped it was true.

Ezarit signaled to the guards, who assembled in the air near the Singer. She smiled at Elna and hugged her. "Glad you are here."

"Be careful, Ezarit," Elna whispered back. "Speed to your wings."

Ezarit winked at Nat, then looked out at the sky. She nodded to the Singer. Ready. She gave me a fierce hug and a kiss. "Stay safe, Kirit."

Then she pushed the shutters wide, unfurled her wings, and leapt from the balcony into the circle of guards waiting for her with bows drawn.

The Singer broke from their formation first, dipping low behind Wirra. I watched from the threshold between our quarters and the balcony until the rest were motes against the otherwise empty sky. Their flight turned west, and disappeared around Densira's broad curve.

For the moment, even Mondarath was still.

Nat moved to pull the shutters closed, but I blocked the way. I wanted to keep watching the sky.

"Kirit, it's Laws," he said, yanking my sleeve. I jerked my arm from his fingers and stepped farther onto the balcony.

"You go inside," I said to the sky. I heard the shutter slam behind me. I'd broken my promise and was going against Laws, but I felt certain that if I took my eyes off the sky, something would happen to Ezarit and her guards.

We'd seen signs of the skymouth migration two days ago. House birds had molted. Silk spiders hid their young. Densira prepared. Watchmen sent black-feathered kaviks to all the tiers. They cackled and shat on the balconies while families read the bone chips they carried.

Attempting to postpone her flight, Ezarit had sent a whipperling to her trading partners in the south and west. They'd replied quickly, "We are not in the migration path." "We can sell our honey elsewhere." There would be none left to mix with Mondarath's herbs for the southeast's medicines.

She made ready. Would not listen to arguments. Sent for Elna early, then helped me strip the balcony.

Mondarath, unlike its neighbors, paid little mind to preparations. The skymouth migration hadn't passed our way for years, they'd said. They didn't take their fruit in. They left their clotheslines and the red banners for Allmoons flapping.

Around me now, our garden was reduced to branches and leaves. Over the low bone outcrop that marked Aunt Bisset's balcony, I saw a glimmer. A bored cousin with a scope, probably. The wind took my hair and tugged the loose tendrils. I leaned out to catch one more glimpse of Ezarit as she passed beyond the tower's curve.

The noise from Mondarath had eased, and the balconies were empty on the towers all around us. I felt both entirely alone and as if the eyes of the city were on me.

I lifted my chin and smiled, letting everyone behind their shutters know I wasn't afraid, when they were. I panned with our scope, searching the sky. A watchman. A guardian.

And I saw it. It tore at my aunt's gnarled trees, then shook loose the ladder down to Nat's. It came straight at me fast and sure: a red rip in the sky, sharp beak edges toothed with ridge upon ridge of glass teeth. Limbs flowed forward like thick tongues.

I dropped the scope.

The mouth opened wider, full of stench and blood.

I felt the rush of air and heard the beat of surging wings, and I screamed. It was a child's scream, not a woman's. I knew I would die in that moment, with tears staining my tunic and that scream soiling my mouth. I heard the bone horns of our tower's watch sound the alarm: We were unlucky once more.

My scream expanded, tore at my throat, my teeth.

The skymouth stopped in its tracks. It hovered there, red and gaping. I saw the glittering teeth and, for a moment, its eyes, large and side-set to let its mouth open even wider. Its breath huffed thick and foul across my face, but it didn't cross the last distance between us. My heart had stopped with fear, but the scream kept on. It spilled from me, softening. As the scream died, the skymouth seemed to move again.

So I hauled in a deep breath through my nose, like we were taught to sing for Allmoons, and I kept screaming.

The skymouth backed up. It closed its jaws. It disappeared into the sky, and soon I saw a distant ripple, headed away from the city.

I tried to laugh, but the sound stuck in my chest and strangled me. Then my eyes betrayed me. Darkness overtook the edges of my vision, and white, wavy lines cut across everything I saw. The hard slats of the shutters counted the bones of my spine as I slid down and came to rest on the balcony floor.

My breathing was too loud in my ears. It roared.

Clouds. I'd shouted down a skymouth and would still die blue-lipped outside my own home? I did not want to die.

Behind me, Nat battered at the shutters. He couldn't open them, I realized groggily, because my body blocked the door.

Cold crept up on me. My fingers prickled, then numbed. I fought my eyelids, but they won, falling closed against the blur that my vision had become.

I thought for a moment I was flying with my mother, far beyond the city. Everything was so blue.

Hands slid under my back and legs. Someone lifted me. The shutters squealed open.

Dishes swept from our table hit the floor and rolled. Lips pressed warm against mine, catching my frozen breath. The rhythm of in and out came back. I heard my name.

When I opened my eyes, I saw the Singer's gray robes first, then the silver lines of his tattoos. His green eyes. The dark hairs in his hawk nose. Behind him, Elna wept and whispered, "On your wings, Singer. Mercy on your wings."

He straightened and turned from me. I heard his voice for the first time, stern and deep, telling Elna, "This is a Singer concern. You will not interfere."