A group of sailors travels together across a tropical country, meeting new people and solving the mystery affecting those there. The crew of PearlHeart is on break after their most recent journey. Rath, One-Eye, his Spirit Lion, and others have chosen to spend it on Delphy, Rath's homeland. However, while traveling to where they are staying for the Summer, cracks begin appearing in different parts of the country and the group agrees to help find the cause in order to protect the Constellation Caves, which lay underground. For readers who love rich characters, mysteries, and traveling across fantasy worlds.