In late 1970s England, we meet Jack, a self-absorbed 15-year-old boy navigating the complexities of life in a post-war prefab home alongside his family: his parents, older sister Julie, younger sister Sue, and little brother Tom. Tragedy strikes when Jack's father suffers a fatal heart attack while they work on the garden path, sending shockwaves through the household. Just a few months later, Jack's mother becomes seriously ill and bedridden, forcing Jack and Julie into unexpected roles as the family's primary caregivers.
Initially, their relationship is fraught with conflict due to Jack's youthful selfishness. However, as they cope with their dire circumstances, an unsettling bond begins to form between the two siblings, leading Jack to develop an inappropriate crush on Julie. With their mother fading and eventually passing away, the siblings face a shocking dilemma. To avoid separation from one another and being placed into foster care, they make the morally questionable decision to conceal her death, entombing her body in a makeshift sarcophagus in the basement using leftover cement from the father's supply.
Without adult supervision, life unravels for Jack, Julie, and their siblings. While Jack grapples with maturation, he neglects personal hygiene, and Sue withdraws into herself, relying on her diary for solace. Julie, on the other hand, begins a relationship with an older man named Derek, stirring feelings of jealousy in Jack. Amidst the chaos, young Tom attempts to explore his identity through cross-dressing and ultimately regresses into childlike dependency.
When Derek starts to suspect something amiss due to a foul odor from the basement, Jack fabricates a story, claiming the cement holds a deceased dog. Unfortunately, Tom reveals the truth about their mother's remains after Derek's inquiry. The tension escalates when Julie reassures Jack that her relationship with Derek lacks intimacy and that they are both living in a peculiar reality.
As they discuss their precarious future, their embrace hints at a deeper emotional connection. However, Derek stumbles upon them in a compromising situation, horrified by their incestuous relationship. Yet, Jack and Julie dismiss Derek's disgust, believing their bond to be normal in light of their shared trauma. In a profound climax, the sound of Derek dismantling the sarcophagus resonates throughout the house as Jack and Julie find solace in each other, falling asleep as police lights ominously flicker in the background. This surreal existence of love, loss, and decay captures the dark complexities of growing up in an unstable environment.
