Below the island, the cave opened into a hall whose walls were carved with maps. Not charts, but snapshots of moments: hurricanes frozen mid-swirl, cannon smoke pinned like white mist, portraits of captains who smiled as if they knew the punchline to every joke. In the center sat a chest, small enough to be held by two hands, decorated with tarnished brass and a single, inlaid star.

It was, by all accounts, nothing of value. Liza, practical, shrugged and went to pry the lid. But Mateo hesitated. He had seen many chests, many greed-flamed faces; he had traded gold for silence and paid silence back in equal measure. This chest felt like something else.

"Trap?" the helmsman asked, checking his knife.

Mateo knelt and ran a hand along the edge. The stone was warm, but not from the sun; it thrummed under his palm, like a heartbeat. When he pressed further, the crack widened by the breadth of a finger, then by a wrist, then a gap the height of a man. From within came a faint, musicless sound: the scrape of old ropes, the sigh of a hidden chamber.

On a wet morning when the sky was iron and the harbor at Nueva Cádiz thrummed with gossip, Mateo put the scrap and the brass mechanism into a small, hand-carved box. He wrote nothing on it. He left it in the hull beneath the mast and dug a shallow grave in the sand of an unremarkable beach. He buried the box and the map of choices with it, and marked the spot only with a bent nail and a bottle cap.

They called it the island of glass: a sliver of sand and white rock far south of any chart, rimmed by reefs that broke the ocean into a constellation of blue. To sailors tired of the ordinary, to captains who kept luck as a loose habit and danger as a close friend, the island promised something else: a crack in the world.

Captain Mateo Reyes found the island by accident. He'd been chasing a rumor across the Caribbean — a merchant with a heavy chest, a priest with a crooked map, a drunk in Port Royal who swore the sea itself hummed there. None of those sources agreed, but the ocean did, in a way: the wind turned and the compass slid, and on the third morning a white line on the horizon resolved into shore.