Tough, sexy and smart Mary Shannon (Mary McCormack) is a U.S. Marshal working for the Federal Witness Protection Program in Albuquerque, New Mexico.
Mary's hands are full with a barrage of newly relocated witnesses. It seems like business as usual in WITSEC, but change is on the horizon. Mary faces a lot of new people and drama in her life, including new WITSEC team member Delia Parmalee and homicide detective Abigail Chaffee. Luckily, Mary can always rely on the support of her loyal, minutiae-obsessed partner, Marshall Mann, and her well-meaning boss Stan McQueen.
Surprisingly, Mary's personal life seems to have stabilized. Younger sister Brandi has her life on track with a steady boyfriend and new job, while their mom Jinx continues to thrive working at the ballet studio. This leaves everyone wondering what Mary will do without personal distractions. Will she finally focus on herself? What happens to the protector when she has no one left to protect?