A mute man known as John Doe, who possesses the mental capacity of a five-year-old, is released from a mental hospital when the state decides they can no longer support his treatment costs. Finding himself living on the streets, he begins to follow the guidance of anyone who crosses his path. Meanwhile, the Producer, portrayed by Ray Liotta, grows increasingly frustrated with method actor Sir Tom Bingsley, who flat out refuses to leave his trailer while filming a biopic about Billy the Kid. To salvage the project and cut costs, the Producer resorts to find a stand-in and stumbles upon John Doe selling oranges. Noticing his uncanny resemblance to Bingsley, he hires him on the spot.
At the same time, Lenny, a struggling publicist, is having a hard time maintaining any clients since his arrival in L.A. He resorts to bribes to gain access to studio lots in search of fresh talent. During one of his escapades, Lenny mishears John Doe’s name as “Latte Pronto,” a mix-up stemming from the Producer's request for coffee. Tragically, when Bingsley dies during an unwise method acting stunt that involves hanging himself, filming for "Billy the Kid" falls to John Doe, now dubbed Pronto. Despite his lack of acting skill and his tendency to look directly into the camera, he captivates his co-stars, such as Kate Beckinsale as Christiana Dior and Adrien Brody as Chad Luxt, who finds inspiration in his so-called avant-garde performance style.
As Lenny devises a plan to elevate Latte Pronto’s career by securing him an agent, Luxt takes him under his wing, introducing him to wild parties and the dazzling yet superficial Hollywood lifestyle. With an unexpected spark, Dior becomes infatuated with Pronto. She convinces him to marry her, and they subsequently adopt several children, creating buzz in the media. "Billy the Kid" turns out to be an astounding success, with critics lauding Pronto's ability to break the fourth wall by looking directly into the camera.
However, at the after party, Lenny's request for assurance that their partnership will continue is met with silence from Pronto, leading to chaos when a security guard attempts to escort him out. A scuffle ensues, and Pronto ultimately faces blame and legal trouble. His agent advises him to stay out of the spotlight but informs him of a new project titled “Mosquito Boy,” directed by Jason Sudeikis playing Lex Tanner.
As filming progresses, Luxt drags Pronto on a night out that ends with both in jail after an altercation with a paparazzo. Despite Luxt being the more aggressive one, Pronto is thrusted into the media’s line of fire, putting further strain on his already tenuous relationship with his representation. During the making of "Mosquito Boy," Pronto sustains an injury that leads to a stand-in taking over much of the shoot. Lenny vows to ensure the film achieves great success, but it crashes at the box office, leading to the dissolution of Pronto's representation.
Frustrated with her husband’s faltering fame and the scandals surrounding him, Dior files for divorce, takes the children, and starts dating Luxt. Left without a home, Pronto moves in with Lenny, and the two bond over shared challenges. But their bond faces a severe test when Lenny suffers a heart attack from an overdose of energy drinks. Pronto remains steadfast at his bedside, only to leave when a fan requests a selfie, leading to a heartbreaking misunderstanding where both feel abandoned by the other.
Eventually, Pronto finds himself back on the streets but forms a friendship with a homeless person named Dagger, saving his life and garnering him media attention that results in a Key to the City award from the Mayor of Los Angeles. Encouraged by the Mayor to consider entering politics on an anti-corporate platform, Pronto is met with threats when he becomes a target of the influential Cote brothers, who go so far as to kidnap him in an attempt to suppress his political aspirations. They threaten his life unless he renounces his political ambitions, promising to restore his acting representation—minus Lenny—and offer him another shot at a film career.
Disillusioned with both the film industry and the duplicity of Hollywood, Pronto steps away from the glitz and glamour. As he wanders the streets, Lenny hunts him down to apologize for exploiting their friendship. In an emotional moment of connection, Pronto finally utters his first words, “I love you too,” solidifying their bond. Together, they leave to share a meal, ready to catch up and face whatever comes next.
