Kaz is a young ghost who can pass through walls—except the library. When his haunt is torn down, he and his ghost family are forced to move. Kaz finds himself separated and drawn to a library, a building he can't penetrate. Inside, he meets Claire, a 'solid' girl who can see and hear him. Together, they discover the library is haunted by other ghosts, and they must solve the mystery of why these spirits are trapped and how to help them move on.