The narrative unfolds in England, primarily within the confines of a family residence where Daniel and his wife, Jane, share their lives with his parents. As the story kicks off, the atmosphere is heavy with solemnity, coinciding with the day of Daniel's father's funeral. Amidst the arrangements for this heart-wrenching event, Daniel and Jane are simultaneously plotting to purchase a flat, eager to break free from the familial nest. However, their plans are complicated by Daniel's brother, Robert, a celebrated novelist residing in New York City, who chooses to splurge on a First Class ticket to England rather than contributing to the funeral expenses. This leaves Daniel with the burden of covering the costs of the burial.
As the family home begins to fill with guests anticipating the funeral service, Daniel finds himself grappling with the daunting task of composing a eulogy, despite the expectation that his literary brother Robert would be the one to deliver poignant words of remembrance. Adding to the chaos are Daniel's cousin Martha and her fiancé Simon, who are desperate to win favor with Martha's finicky father, Victor. Their aspirations take a turn for the worse when Martha, in an attempt to ease Simon's nerves, mistakenly administers what she believes is Valium, but is actually a potent hallucinogenic drug concocted by her brother Troy, who is studying pharmacy.
As the funeral commences, Simon starts feeling the potent effects of the drug, culminating in a bizarre episode where he mistakenly believes the coffin is moving. In a moment of panic, he tips it over, leading to a comical, albeit distressing, scene where the body wreaks havoc on the solemn occasion. Amidst the ensuing pandemonium, Martha pulls Simon outside to confront her father's strict stance against their relationship. In the midst of the confusion, Simon becomes overwhelmed and locks himself in the upstairs bathroom, leading to a comedic yet touching confrontation between Martha and Justin, a man from her past with whom she had regrettable encounters.
In an unexpected twist, it is revealed that Peter, a dwarf who introduces himself to Daniel, carries secrets of his own — he was in a relationship with their father. Expressing his dissatisfaction with being left out of the inheritance, Peter tries to leverage this information for £15,000, plunging Daniel and Robert into a frantic state. In a misguided attempt to manage Peter's turmoil, they inadvertently offer him the same hallucinogenic drug, believing it to be Valium. As the confusion escalates, Peter, buoyed by the effects of the drug, jumps onto the sofa, crashes, and appears to be lifeless.
The narrative reaches a crescendo when Daniel and Robert are forced to hastily dispose of Peter's body, opting to conceal it within the coffin alongside their father. Just when the eulogy moments seem to settle, Peter springs back to life, sending the service into further disarray as compromising photos spill out of his pocket for all to witness, including the grieving widow. Despite the chaos, Daniel steps up to honor his father, a man filled with secrets, by delivering a heartfelt tribute.
As the night settles in, Robert discusses plans to take their mother to New York, allowing Daniel and Jane the independence of finally moving into their own apartment. However, their plans are swiftly interrupted by Jane, who reveals that Uncle Alfie will be spending the night due to a panic attack triggered by the earlier body-moving incident. Shockingly, she mentions she unknowingly gave Alfie some of Troy's hallucinogenic, leading to a humorous yet alarming scene where Alfie ends up on the roof, stark naked, echoing Simon's earlier antics and lamenting the overwhelming greenery of his surroundings.
