Workers dig into the earth to repair the Bodie Island Lighthouse Library's foundations. But the digging halts when Lucy pulls a battered tin box containing a Civil War-era diary from the pit. Tucked inside is a hand drawn map of the Outer Banks accompanied by a page written in an indecipherable code. Later that night, Lucy finds the body of historical society member Jeremy Hughes inside the library. Clearly Jeremy was not the only one who broke into the library, the map and the coded page are missing. But when the library has a second break in, it becomes clear that someone is determined to solve that code.