The moon fell on the night Sera Vale turned twenty-one.

Not the whole moon.

Only a piece of it.

A silver fragment crossed the night sky like a burning comet and disappeared beyond the frozen ocean.

Sera watched from the window of the lighthouse.

She had spent her entire life there with her grandmother.

No cities.

No crowded streets.

No advanced technology.

Only the sea, the lighthouse, and the endless night.

Her grandmother always told her that the world had once been different.

There had been seven moons.

There had been forests taller than mountains.

There had been cities floating above the clouds.

Sera had never believed her.

Until tonight.

The lighthouse suddenly went dark.

Sera turned.

“Grandmother?”

No answer.

She walked downstairs.

The old woman was standing beside the radio.

Her face had gone pale.

“What happened?”

Her grandmother looked at the sky.

“The moon has opened.”

Sera frowned.

“What does that mean?”

Her grandmother reached beneath the table and pulled out a small metal box.

She handed it to Sera.

“Your mother wanted you to have this when you turned twenty-one.”

Sera stared at the box.

“My mother?”

She had never known her mother.

She had been told she died before Sera was born.

“Why didn’t you give it to me before?”

“Because it wasn’t safe.”

The box suddenly unlocked.

Inside was a small crystal.

It glowed with a soft blue light.

Sera touched it.

A hologram appeared above the table.

A woman stood inside the projection.

Young.

Beautiful.

And strangely familiar.

Sera’s breath caught.

“Mom?”

The woman looked directly at her.

“If you’re seeing this, then Aetheria has awakened.”

Sera stepped closer.

The hologram continued.

“You must leave the lighthouse before sunrise.”

“Why?”

The recording did not answer.

Instead, the woman said:

“Never trust the people wearing white.”

The hologram disappeared.

Sera looked at her grandmother.

“What is Aetheria?”

Her grandmother’s eyes filled with tears.

“The city beneath the ocean.”

Sera stared at her.

“There is no city beneath the ocean.”

“There wasn’t.”

A deep sound suddenly rolled across the sea.

The lighthouse windows shook.

Outside, the ocean began glowing blue.

Something enormous was rising beneath the water.

Sera ran outside.

The sea was moving backward.

A massive structure emerged from the ocean.

Towers.

Bridges.

Glass domes.

An entire city rising from beneath the waves.

Lights awakened one by one.

Then every tower turned toward the lighthouse.

A voice came through the crystal in Sera’s hand.

“Welcome home, Princess Sera.”

She froze.

“Princess?”

Her grandmother stood behind her.

“I hoped you’d never have to know.”

Suddenly, the sky filled with aircraft.

Dozens of white ships descended toward the lighthouse.

Her grandmother grabbed Sera’s hand.

“We have to run.”

“Who are they?”

“The people your mother warned you about.”

The ships opened.

Soldiers in white armor stepped onto the shore.

Their commander removed his helmet.

He was young.

With silver eyes.

He looked directly at Sera.

“Princess.”

Sera stepped backward.

The commander smiled.

“Your kingdom has been waiting for you.”

Behind him, the underwater city continued rising.

And somewhere beneath the ocean, something ancient began to wake.