U.S. Marshal Mary Shannon must hunt down witnesses for federal cases in the witness protection program while also managing a rather dysfunctional family and her own personal life.U.S. Marshal Mary Shannon must hunt down witnesses for federal cases in the witness protection program while also managing a rather dysfunctional family and her own personal life.U.S. Marshal Mary Shannon must hunt down witnesses for federal cases in the witness protection program while also managing a rather dysfunctional family and her own personal life.