Mary Shannon is a U.S. Marshal in the highly secretive witness protection branch who spends her time relocating federal witnesses - whether notorious criminals or innocent bystanders who found themselves in the wrong place at the wrong time - each of whom are wanted dead. Based out of Albuquerque, New Mexico, Mary works side-by-side with her partner, Marshall Mann, who is the polar opposite of herself but a perfect partner nonetheless.
While not putting her life on the line to protect federal witnesses, Mary must attempt to manage her dysfunctional family, including overly dependent mother, Jinx, and younger sister, Brandi, both of whom live under the same roof as Mary. After dealing with her career and family, Mary has little time for boyfriend Raphael Ramirez, a baseball player, but relies on him to keep her sane whenever she needs it most.