At the lakeside family cottage, Todd [Tyler Labine] dreams of a perfect proposal to Cammie [Malin Åkerman], hoping to begin a life together in quiet happiness. But the visit from his laid-back brother, Salinger Chipowski [Dan Petronijevic], and Salinger’s free-spirited girlfriend, Masha [Lucy Punch], upends the plans. What starts as a simple family weekend quickly spirals into tragedy when Todd accidentally kills his brother with an axe. After he confesses to Cammie, the two of them hatch a dangerous plan to hide the truth by eliminating Masha as well.
In a tense kitchen scene, Masha is caught off guard as she turns from the stove where she’s cooking mushrooms. Todd is about to strike, but Cammie acts first, knocking Masha out with a frying pan. Masha collapses to the floor, seized by a sudden spell of seizures, and Cammie quickly covers her with a tarp before delivering a brutal, decisive blow. The two of them then chop up the bodies and dispose of them in the lake, all while trying to maintain a veneer of normalcy on their way to the island. There, Todd musters the courage to propose again, and Cammie accepts, sealing the lie with a ring-warming yes.
As they return to the mainland, the couple discovers that Salinger has invited many guests to the cottage for a party, and the house is suddenly crowded with friends who tracking the clues around Masha’s disappearance. A friend among Salinger’s circle grows suspicious, catching Cammie in a mismatch of stories, and turning the attention toward the couple. The friend shares what he knows with Todd, noting how much Salinger seems to value and love him, and he even spots a cut above Todd’s head that belies the timeline they’ve been selling. The discrepancy gnaws at them, yet Cammie remains fixated on preserving their future together, even as Todd’s guilt over his brother’s death and his indirect role in Masha’s death weighs on him.
Todd, overwhelmed by the consequences of their actions, reveals to Cammie that he intends to turn himself in. Yet Cammie’s resolve hardens into a fixation on protecting their dream of marriage, and she decides to frame someone else for Salinger and Masha’s deaths. The split between truth and safety grows more dangerous, and Todd realizes that Cammie will go to any length to keep him by her side. He attempts to end the relationship and drive to the police station to confess, but Cammie barrels after him in a reckless chase, determined to pull him back into the life she imagines for them.
The pursuit ends in a dramatic standoff: Todd arrives first at the police line, ready to spill the truth, while Cammie swerves to ram him with her car. A female officer fires through the windshield, narrowly missing Todd as he braces for impact. In the chaos, Cammie suffers several gunshot wounds to the chest—and, in a final, brutal twist, she crashes the car and dies near Todd. As Cammie dies, she clutches the engagement ring with her teeth and slips away.
Time jumps to a year later. Todd survives the gunshot and is wheeled onto the cottage dock by his father, the memories of what happened still fading and resurfacing in fragments. He comments on how nice the cottage looks and asks again about his mother and brother, only to be met with the stark sight of surgical scars on his head. The memory loss underscores a haunting, never-ending cycle of what was done and what remains unresolved, leaving a man trapped in the aftermath of fear, love, and a life that cannot be reclaimed.
