Summer is deadly in the mountain community of Mason County, Virginia.

Deputy Sheriff Tom Bridger and his girlfriend, veterinarian Rachel Goddard, are caught in a maelstrom of lies that stretch far into the past and suspicions that threaten the future when two Mason County residents are killed. Cam and Meredith Taylor are murdered within hours of one another, and Rachel is dragged into the case because she heard—but didn't see—Cam's murder. The Taylors arrived in Mason County as volunteers in the 1960s War on Poverty, and they stayed on, making loyal friends and bitter enemies. The victims' daughter is Tom's former girlfriend, Leslie. She returns home to see justice done—and to win Tom back from Rachel.

The prime suspect is newcomer Ben Hern, Rachel's childhood friend, and she is desperate to prove him innocent. Leslie pushes for Hern's arrest and launches a campaign of intimidation against Rachel. With the killer targeting Rachel and the community clamoring for an arrest, Tom and Rachel must decide who they can trust.