"The Mediator Series" is a young adult book series written by Meg Cabot. It follows the story of Suze Simon, a teenage girl who can see and communicate with ghosts. Suze's unique ability leads her to help spirits resolve their unfinished business, often putting her in challenging and sometimes dangerous situations. The series consists of six books, starting with "Shadowland" and concluding with "Heaven Sent." Throughout the series, Suze navigates her relationships with friends, family, and the living, while also dealing with the complexities of her supernatural encounters. The blend of romance, humor, and paranormal elements makes it a popular choice among readers.