When a witness comes forward to testify against the worst-of-the-worst criminals, the U.S. Marshals are called in to protect them before and after they testify - helping them transition into the anonymous safety of the Witness Protection Program. Meet Mary Shannon (Mary McCormack), one such U.S. Marshal, a beautiful and strong-willed woman who balances her duties baby sitting targets with her responsibilities to her dysfunctional family, which includes her delinquent sister (Nichole Hiltz) and her eccentric mother (Academy Award nominee Lesley Ann Warren).