In a quiet coastal town, a mysterious journal is found, tucked between the pages of a random book. It belongs to an explorer who vanished a century ago while searching for a mythical island believed to grant immortality. The journal, filled with cryptic symbols and half-finished maps, falls into the hands of Seraphina, a curious librarian who has always felt drawn to the ocean but never understood why. As Seraphina decodes the journal, she uncovers long-buried secrets about her town and her own lineage. She discovers that her ancestors were part of the last expedition to the island, but none of them ever returned. Driven by a desire to uncover the truth and finally understand the connection, she assembles a small group of misfits, including a curious cartographer, a daring treasure hunter, and a historian who knows to pay attention to detail. Together, they embark on a life-threatening journey across treacherous waters, facing mystical sea creatures, ancient traps, and a rival crew chasing the same prize. Along the way, they confront the possibility that the island's immortality might come at a terrible cost. The deeper they go, the more Seraphina realizes that some mysteries are better left buried.