Unmarked features twenty photographs by Stephen Chalmers, and twenty satellite images of the same locations. These images are accompanied by a text on the American landscape. It is only at the very end of the book that the reader is given the clues to decipher the story behind the all the photographs were taken at sites where serial murderers disposed of their victims. The research to locate these sites was performed through the public records of closed serial killer cases and historic investigative photographs. Chalmers then used GPS technology and mapping software, visited the exact spot where the bodies were found, and photographed the landscape.