In the Mid-Coast town of Camden, Maine, Matt and Ruth Fowler enjoy a happy marriage and a good relationship with their son Frank, a recent college graduate who has come home for the summer. Frank has fallen in love with a divorced older woman with children, Natalie Strout.Frank is about to begin post graduate school for architecture, but is having second thoughts and considering staying in town to continue working as a fisherman and, more importantly, to be near Natalie and her kids. Natalie's ex-husband, Richard Strout, tries to find a way into his ex-wife and children's lives, going to increasingly violent lengths to get his intentions across to Natalie, including assaulting Frank. Ruth is openly concerned about Frank's relationship with Natalie, while Matt thinks it is only a fling. Frank resists Ruth's insistence he report Richard's violence to the police, but neither she nor Matt call them either.Frank rushes to Natalie's home after receiving a frightened phone call from one of her children. He arrives to find the living room trashed, and Natalie in distress. She tells him Richard just left, and pleads with him not to call the police, but Richard returns almost immediately, still in a rage. Natalie takes the boys upstairs, and Frank insists through the locked front door that Richard leave. He feigns doing so, only to break in through the back door and kill Frank with a handgun.Though equally devastated, Matt and Ruth grieve in different ways, with Matt putting on a brave face while Ruth becomes reclusive and quiet. Richard is set free on bail, paid by his well-to-do family, and both Matt and Ruth are forced to see him around town.The couple retreat with friends Willis and Katie Grinnel to a secluded cottage for a weekend, but Ruth is distant; she rarely contributes to conversation, eyes Matt's drinking suspiciously, and sleeps most of the ride home. The next Saturday, Matt tells Ruth he's going into the office, but he instead goes to the convenience store where Natalie works. The two speak briefly, but Matt begins to become emotional, so he leaves. He goes fishing, and badly cuts his right index finger hauling lobster traps.The tension between Matt and Ruth increases when their lawyer informs them that the lack of an eyewitness to Frank's shooting means Richard will instead be charged with accidental manslaughter, and will likely only serve five to ten years in prison. Ruth is openly distraught by this, Matt seems deflated. He and Willis spend the evening drinking and lamenting the injustice of the situation.Natalie approaches Ruth at work and attempts to apologize, but Ruth slaps her before dismissively returning to her papers. Natalie leaves in tears. Later that same day, Ruth accidentally then runs into Richard again while buying cigarettes.When she returns home, an argument erupts between the couple in which each one confronts and emotionally savages the other; Matt lambastes Ruth for being an overbearing presence in Frank's youth, while Ruth in turn chastises Matt for showing little grief for their deceased son. A little girl knocks on the door, interrupting them, and Matt buys $10 worth of chocolate from her. He returns, measured now, and apologizes to Ruth, who apologizes in turn and, breaking down, tells Matt about seeing Natalie and Richard. The two embrace. With the air cleared, the couple is finally able to find common ground in their grief.Matt then abducts Richard at gunpoint, saying he's arranged for Richard to jump bail and leave the state, so as to spare them the pain of seeing him in Camden. He forces Richard to "pack clothes for warm weather" and plants a train schedule in his apartment. He forces Richard to drive them out to the Grinnel cabin, where Willis is waiting with another vehicle. He begins to load Richard's belongings, but Matt hesitates - and then shoots Richard once in the shoulder and twice in the back, killing him. Willis is shocked, admonishing Matt for not following the plan. Matt responds simply that he couldn't wait. The two successfully bury Richard's body deep in the woods beyond the cabin, but are stuck unexpectedly at a bridge crossing on their return home. Willis laments that this cost them nearly an hour - meaning they arrive back in town just after sunrise at 4:00am instead of in darkness at 3:00am - and Matt apologizes.Matt returns home and wraps his clothes in an old blanket, before washing himself in the downstairs sink. He returns to the bedroom upstairs to find Ruth awake and smoking in bed. She asks him, "Did you do it?" Matt appears troubled and unresponsive. He climbs into bed and then turns away from her. Finally, Ruth gets up to make coffee. Matt rolls over onto his back and removes the band-aid from the finger he injured hauling traps - his trigger finger - to examine the healing wound underneath. Ruth calls from the kitchen, "Matt, do you want coffee?" Matt doesn't answer.