In December 1980, an unlikely action show debuted on CBS. "Magnum P.I." told the story of Vietnam War veteran Thomas Magnum and his work in Hawaii as a private investigator for an elusive, millionaire mystery writer. The series lasted for eight seasons and became a huge financial and critical success, but the show had its own backstage dramas. From the role that Selleck almost didn't take, the tragedy that struck the set, and the personal stumbling blocks that faced cast members, the documentary examines the successful private-eye action series.