Alcoholic Freddie Quell, portrayed by Joaquin Phoenix, is a World War II veteran grappling with the demons of post-traumatic stress disorder as he struggles to find his place in society after the war. Initially, he secures a job as a photographer at a local department store, where he captures cherished family moments. Unfortunately, his temper flares, leading to his dismissal after he drunkenly assaults a customer.
Freddie’s next stint is on a cabbage farm, but disaster strikes when one of his homemade alcoholic concoctions, which is dubious at best, ends up poisoning an elderly coworker. Chased away from the farm, Freddie becomes a drifter, wandering aimlessly until one fateful night when he drunkenly boards a yacht owned by Lancaster Dodd, played by Philip Seymour Hoffman, the charismatic leader of a philosophical movement known as The Cause. Dodd, intrigued by Freddie’s presence, extends him a welcome and even invites him to his daughter’s wedding, using the occasion to draw Freddie closer into his world.
As Freddie immerses himself in The Cause, he undergoes a grueling psychological exercise known as Processing, where his deeply buried traumas resurface. This probing reveals a tumultuous past: his father’s death, his mother’s institutionalization, a potentially troubling relationship with his aunt, and the painful memories of abandoning his first love, Doris, played by Madisen Beaty. Captivated by the teachings of Dodd, Freddie finds himself on a path with Dodd, spreading the message of The Cause along the East Coast. However, Freddie's erratic behavior and heavy drinking continue to pose challenges, culminating in an outburst at a dinner party in New York where he violently reacts to criticisms aimed at Dodd.
As concerns about Freddie's erratic ways grow among members of The Cause, Dodd’s steadfast belief in Freddie’s potential becomes a point of contention. During a visit to Philadelphia, Dodd's wife, Peggy (portrayed by Amy Adams), implores Freddie to quit drinking if he wishes to remain with them, to which he superficially agrees, harboring no true intent of change. Tensions rise when Freddie confronts Dodd's son Val, played by Jesse Plemons, about his apparent lack of respect for Dodd’s teachings. Val challenges Freddie, revealing the unsettling truth that Dodd's principles are largely improvised and unverified.
As Dodd faces legal troubles for practicing medicine without proper qualifications, both he and Freddie find themselves in jail, where Freddie's rage leads him to engage in destructive behavior. Even as Dodd attempts to provide guidance from a neighboring cell, Freddie erupts with questions, challenging everything Dodd stands for, resulting in a heated exchange. However, their bond is somewhat rekindled upon their release, even as other followers of The Cause grow wary of Freddie, suspecting his sanity.
Despite his commitment to Dodd’s teachings, Freddie’s frustration mounts as he experiences a lack of meaningful progress during their exercises. His volatile behavior and inability to accept repetitive practices lead to confrontations, particularly when he fiercely defends Dodd and his teachings against external criticisms. An incident at a publisher's office leaves Freddie in a fit of rage, demonstrating the fragile state of their relationship.
The issues culminate when an exercise involving Freddie racing a motorcycle towards a distant target ends with him abandoning Dodd in the desert and choosing to leave The Cause. In a bittersweet turn, Freddie attempts to reconnect with Doris, only to learn that her life has moved on without him, leaving him with a mix of disappointment and acceptance.
A surreal encounter occurs while Freddie sleeps in a theater, imagined as a “vision” of Dodd, beckoning him to England. Taking this call literally, Freddie travels across the Atlantic, only to find Dodd’s wife asserting that he has no desire to change and shouldn't be part of their movement. Finally acknowledging the truth in his wife's words, Dodd realizes that Freddie must chart his own course. He presents Freddie with a stark ultimatum: commit himself to The Cause or leave, never to return. Ultimately, Freddie chooses the latter.
After parting ways, Freddie meets a woman in a pub and finds momentary solace in physical companionship, all while echoing the probing questions Dodd had once posed to him during their initial encounter. The narrative concludes with a poignant image of Freddie on the beach, lying beside a sand sculpture of a woman he once defiled, encapsulating his tumultuous journey in search of purpose and reconciliation with his past.
