The Cartographer's Apprentice

Nerin Voss has spent six years grinding pigments and ruling grid lines in the chart-house of Port Anselm, copying the same coastlines her guild has sold for a century. She is good at it — good enough to notice, one grey afternoon, that every chart in the vault agrees on something that isn't true. Forty leagues off the Anselm shoals, where three older maps show an island, the guild's charts show open water. All of them. In the same hand.

An apprentice who asks the wrong question loses her indenture. Nerin asks it anyway — and finds that the island isn't the only thing her masters have been paid to leave off the map.