The only life Tress has known on her island home in an emerald-green ocean has been a simple one - collecting cups brought by sailors from faraway lands and listening to stories told by her friend Charlie. When Charlie is captured by the Sorceress of the deadly Midnight Sea, Tress stows away on a ship to rescue him, navigating oceans made of dangerous spores where a single drop of water can mean instant death. Narrated by Hoid, the Cosmere's most enigmatic recurring character, Tress of the Emerald Sea is a standalone adventure inspired by The Princess Bride - whimsical in tone but rich with Sanderson's trademark worldbuilding and an inventive magic system based on the aethers, a form of Investiture being introduced to the broader Cosmere.