Having recently decided to make Purgatory Falls her home, Brooke dives into helping with the annual Founders' Week events. The mermaid (and occasional amateur sleuth) is tasked with helping tourists, students and history enthusiasts collect stamps for a special memento, but quickly gets swept into the search for a stolen bracelet--which leads to the discovery of a dead body.
Meanwhile, a decades-old hunt for treasure foretold to be discovered during Founders' Week has turned dangerous in a way that hits close to home for Brooke. Her best friend Twyla's home--a large tree that is a part of the tree nymph herself--is attacked by treasure hunters. Rather than sit around and hope, Brooke decides to end the frenzy before anyone else is hurt by finding the treasure herself. But Brooke's own history might be wrapped up in the history of the town and searching for the treasure puts her in more danger than she has ever been in before.