Chapter 1

The early morning air smelled of salt and wet sand. Gulls cried overhead. Sofia had come to this cove a hundred times, but never found anything more interesting than a crab shell or a fishing float. Now she had something real. Her mother’s stories were true.

She reached into the cold water and snatched the shard before the next wave could claim it. It still felt warm, as if it held a small sun inside. She turned it over. The spiral seemed to shimmer when she tilted it. She wanted—needed—to know where it had come from. Maybe there were more. Maybe the city wasn’t lost at all, just hidden.

Sofia looked up the beach. The tide was coming in, and she had promised to be home by breakfast. But the shard in her hand was a promise of its own. She made a choice. She would go to the rocky point where the old lighthouse stood. Her mother had said the lighthouse was built on the ruins of an Aegiran watchtower. If there was a place where the city’s secrets had washed ashore, it would be there.

She scrambled over the wet rocks, careful not to slip. The point stretched out like a stone finger pointing at the open sea. The lighthouse was a stub of moss-covered brick, its lamp long gone. At its base, half buried in gravel, a flat stone caught her eye. It had a shallow depression in the shape of a spiral.

Sofia knelt and brushed the debris away. The stone was the size of a dinner plate, and the depression matched the shard in her hand. Her heart pounded. She knelt and pressed the shard into the groove. It slid into place with a soft click.

The stone grew cold. Not the chill of the sea, but a deep, ancient cold that made her fingers ache. She tried to pull the shard back, but it stuck. Then the stone—and the ground beneath it—trembled.

Sofia jerked her hands away. The shard stayed in the stone, glowing faintly blue. The gravel shifted. A crack appeared in the rock at the lighthouse’s foundation, and with a grinding sound, a slab of stone slid sideways, revealing a dark opening that led down into the cliff. Steps—rough and worn—descended into what looked like a tunnel. The air that rose from it smelled of damp stone and something metallic.

Sofia stared into the dark. The shard in the stone still glowed, casting a faint light on the first few steps. The tunnel sloped steeply, then turned a corner. She couldn’t see the bottom.

She looked back toward the cove. The tide was halfway up the beach now. The sun was climbing over the mainland hills. She had a choice: go back to breakfast, or go down.

The shard’s warmth seemed to call her. She remembered her mother’s voice, telling the story of Aegira: a city of towers and gardens, lost to the sea in a single night. A city that was not destroyed, but hidden, waiting to be found.

Sofia took a breath. She placed one hand on the cold stone wall and stepped onto the first stair. The door behind her did not close. She continued down, the glow of the shard guiding her, until she turned the corner and the daylight vanished.

Her footsteps echoed in the narrow space. The tunnel opened into a chamber, its walls covered in carvings of fish and spirals, and in the center, a pool of water so clear it looked like glass. At the bottom of the pool, far below, something gleamed.

Sofia knelt at the edge. The water was perfectly still. She could see the shape of a building down there—a crumbled archway, a courtyard paved with white stone. And beyond it, more shapes, stretching into the darkness of the deep.

The sunken city. She had found it.

But the pool was deep, and she could not swim down to it. She needed air, a light that wouldn’t go out, a way to reach the bottom. The shard in the stone above was not enough. She needed something more.

A soft clink sounded behind her. She spun around. The stone door at the top of the stairs was sliding shut. The light from outside narrowed to a slit, then vanished. She was in darkness.

Sofia’s breath caught. She was trapped. But the chamber was not completely dark. The pool emitted a faint blue glow—perhaps the gleaming object at its bottom. She could see the carvings on the walls, the water, the shapes below.

She stood slowly, listening. The only sound was the distant drip of water. She was alone with the city of the deep. And she had no way back.

The only way was down.