Socially awkward garbageman Simon Grim leads a dull existence alongside his sister, Fay, and their mother, Mary, who grapples with profound depression. Their lives take an unexpected turn when Henry Fool, a probationer recently released from prison due to a conviction for statutory rape, moves into their basement and starts to meddle in their day-to-day dynamics. Noticing Simon's budding interest in literature, Henry inspires him to jot down his thoughts in a notebook. Simon's scribblings eventually evolve into a poem, which Henry urges him to seek publication for, despite its dismissal by many as lewd and scatological.
A pivotal meeting occurs when Simon approaches a publisher named Angus, allegedly an acquaintance of Henry's. However, Angus rejects Simon's manuscript, feigning ignorance of Henry's identity until his secretary inadvertently reveals that Henry had worked as a janitor in Angus' office. At the same time, Henry possesses his collection of notebooks he dubs his "Confession," which chronicles his enigmatic past—a piece of work he’s been hesitant to share with anyone.
As Henry's capricious lifestyle impacts the lives of those nearby, he ends up marrying Fay after impregnating her. Following his lead, Fay takes the bold step of uploading snippets of Simon's poem to the Internet, where it ignites a global outcry, drawing admiration from those who commend Simon as a transgressive genius while inciting outrage from conservative politicians who deem his work inappropriate. Soon after, Angus reapproaches Simon with an offer—$200,000 upfront and a 60/40 royalty split for the publication of his poem.
Henry is unsettled about the impending responsibility of fatherhood, fearing that balancing a job to support his family would stifle his writing ambitions. In a show of gratitude, Simon pledges to urge Angus to publish Henry's work as part of his own contract. Upon finally gaining access to Henry's notebooks, however, Simon is less than impressed but agrees to present it to Angus as promised. Angus, lacking interest in the "Confession," refuses to publish it, prompting Simon to rethink his commitment to Henry. As Fay gives birth to a son, Simon breaks the news of Angus’ rejection and reveals he has signed his own publishing deal, leading to a heated argument with Henry, who is visibly distressed.
Fast forward seven years, and Henry has taken a job at the garbage company once employed by Simon, who has just been awarded the Nobel Prize in Literature. One fateful night, a young girl from the neighborhood reveals to Henry that her stepfather has been abusing her mother, offering a grim ultimatum if Henry will eliminate him. When Henry shows up at their home to check on the situation, he is brutally attacked by the drunken man and is forced to defend himself, resulting in the man's death. Past convictions, alongside the girl's testimony, paint Henry in a negative light.
In a twist of fate, Henry and Fay's son, Ned, seeks out Simon to help his father. Despite being on his way to catch a flight to accept his Nobel Prize, Simon alters his travel plans: he gives his passport and ticket to Henry. Although they arrive late at the airport, Simon's celebrated status compels the airline to hold the plane for them. As the flight attendants hastily usher Henry—disguised as Simon—towards the plane, Henry hesitates, glancing back one last time. The conclusion captures an intimate moment of determination as Henry rushes forward, luggage in hand.
