A young boy dashes out of a home into the overgrown grass surrounding a decaying city, accompanied by a nostalgic melody reminiscent of the 1920s. As viewers are introduced to the desolate setting through a slow montage, they see a family confronting the grim reality of their crumbling neighborhood. The older brother, Bones, bids farewell to a neighbor fleeing the area, who earnestly advises him to escape while he still can.
In this forgotten world, Bones scavenges through vacant buildings in search of copper to collect. However, a territorial figure named Bully patrols the area with a loudspeaker, warning against encroaching on his territory. When Bones is discovered, he hastily drops his copper loot and makes a run for it.
Meanwhile, their mother, Billy, finds herself in a precarious situation, having fallen three months behind on her mortgage. During a visit to the bank, the manager, Dave (Ben Mendelsohn), who struggles with hearing, presents her with an unsolicited job offer, all while expressing his admiration for her beauty. Unwilling to part with the house, which once belonged to her grandmother, Billy deceptively assures Bones that they are financially secure when he inquires about their mortgage status.
Across the street, a girl named Rat sings a melancholic tune in her bedroom while her grandmother sits engrossed in old television shows. The following morning, a demolition crew begins to raze the house opposite theirs, marking Bones’s home with a conspicuous red “D.” Eventually, Billy confesses the truth regarding their financial troubles to Bones.
Later that day, Bones encounters Bully once more during his scavenging activities but manages to elude him once again. Seeking their escape route, he is drawn to a pathway that leads to the dam. In a twist of fate, Billy decides to accept the job offer at the bank, hoping for a brighter future.
Back in the scrapyard, Bones's attempts to sell his copper are thwarted due to Bully's looming threat. A chilling story tales of a young Chinese boy, whom Bones had caught, and the horrific act that followed leads him to question his own struggles. As night falls, Rat expresses her curiosities about the submerged town at the bottom of the reservoir. She recounts how an evil curse befell Lost River after its towns were flooded, marking it as a place of misfortune.
Billy makes her way to work, stepping into a theatrical world of gore and theatrics. As she traverses through a grotesque performance realm, she encounters Cat, who plays a pivotal role in her new job. Rat returns home to find her grandmother fixated on nostalgic wedding footage, feeling a deep sense of loss for the days gone by.
When Bones ventures onto the dam in search of clues about the drowned town, he stumbles upon ominous clues from the past, including traces of a forgotten prehistoric park. Meanwhile, Billy's life at the theater takes a turn as she is guided through disturbing performances where willing participants can express their frustrations without consequences.
As their lives intertwine amidst the chaos of their environment, different tensions arise, forcing them to confront their realities. The stage shows grow increasingly grotesque, and while Bones and Rat navigate their friendship, Billy finds herself in a compromising position at the theater.
Through a series of harrowing encounters, Bully's threats escalate, and as the climax nears, a burning house signals an impending disaster. Bones, driven to protect his loved ones and break the mythical curse of their town, confronts Bully and sets out on a perilous journey into the depths of the dam to retrieve a significant artifact that could change their fate.
In a grim showdown at the club, Billy faces off against Dave, managing to turn the tide just as danger closes in on them. As fires rage and darkness falls upon their homes, the family's journey of survival culminates in a powerful reunion. Through this harrowing yet poignant tale, themes of loyalty, heartbreak, and resilience emerge, ultimately leaving the audience with a lingering sense of hope as they leave their burning home behind in search of a brighter future.
