Josefina "Jo" Lupo is Eureka's deputy sheriff, a New Jersey girl and former U.S. Army Ranger. The eccentric residents of Eureka try her patience, but they've grown accustomed to her bluster and appreciate her dedication to their safety. At first, Jo is resentful of having to report to an outsider when Jack Carter is given the sheriff's job, but she comes to gain respect for his talents and becomes his trusted partner in maintaining the peace. Now, if only her personal life could be as rewarding….