The sea rose in the night and never went back down. By dawn the mountains were islands, and the cities everyone remembered were just rumors now. Iyla rowed to her father's old boathouse, where her brother Sefu was already waiting. They hadn't spoken in three years. But the will named them both, and it named one thing: the diving bell. It hung from the rafters, heavy brass and green with age. Folded inside it were a waxed map and a single key.

Iyla unfolded the map first. It showed the drowned city below them, with one building marked in red: the old bank vault, deep down in the dark water. "He hid something there," she said. "That's what the key opens." Sefu looked at the cold sea. "That's ninety fathoms down. But the bell could take us."

Halfway down, the chain jammed. The bell stopped with a jolt and swung in the black water. "It's caught on something," Sefu said, his voice tight. Through the small window, Iyla saw a tangle of old fishing nets wrapped around the rafters of a sunken roof, holding them fast.

Instead of cutting free, Iyla studied the sunken roof holding them. "That's the old library," she whispered. "Dad used to bring me here." A second door hung open below, and inside she could see shelves still stacked with sealed metal cases. Maybe the bank wasn't the only secret down here after all.

Iyla pried open one metal case from the library. Inside were her father's notebooks, full of maps to dozens of hidden caches all along the drowned coast. He hadn't saved one thing. He'd been planning to save everyone. "This is bigger than us," she said. "We're going to need help. A lot of it."