The film unfolds in Camden, Maine, where we meet Ruth Fowler (Sissy Spacek) and Matt Fowler (Tom Wilkinson), a couple enjoying a seemingly blissful marriage with their son Frank. Frank, who has recently graduated from college, returns home for the summer. As a respected figure in the community, Matt tends to his medical practice while Frank grapples with his feelings for an older woman, Natalie Strout.
Natalie is a single mother of two boys, Jason and Duncan, and is stuck in an unsettling situation with her abusive ex-husband, Richard Strout. Richard, fueled by a volatile rage directed towards Frank and Natalie's relationship, resorts to escalating threats and actions. As Natalie tries to shield her children from Richard's influence, Ruth grows increasingly wary of Frank's involvement with her. Despite Frank's assurances that his bond with Natalie is merely a summer affair, the stakes rise when Richard discovers them together.
One fateful encounter spirals into tragedy when Richard violently confronts Frank in a park, leading Frank to refuse legal action for Natalie's sake. Tensions crescendo when Frank responds to a desperate call from Natalie's children, only to stumble into a scene of chaos at her home. In a shocking turn of events, Richard re-enters with a gun, resulting in the tragic murder of Frank. Natalie, arriving moments later, is horrified to find Richard standing over her son with blood on his hands.
As they navigate their grief, both Ruth and Matt respond differently to their loss. Ruth becomes emotionally withdrawn, while Matt attempts to mask his pain with a veneer of normalcy. The couple's strife deepens when they learn that the lack of eyewitness accounts may allow Richard to evade serious consequences, potentially facing only a few years in prison under manslaughter charges. This realization adds to their despair, especially as they encounter Richard throughout their daily lives.
To cope, Matt dives into work and memories of fishing, reminiscing about the joys he shared with Frank. In a confrontation marked by anger and sorrow, tensions flare when Ruth slaps Natalie during an unexpected meeting. They even retreat to a cottage with friends to find solace but end up confronting uncomfortable truths about their parenting.
In a moment of desperation, Matt abducts Richard at gunpoint, revealing his intention to force Richard into fleeing the area to lessen their pain. However, in a shocking twist, Matt takes Richard's life in cold blood, burying him in the woods as both men grapple with the consequences of their actions. Upon returning home, a perturbed Matt encounters Ruth, who questions him about the night’s events, leaving the audience uncertain about the future of their relationship, culminating in an eerie silence that hangs heavy in the air.
