The film begins with Josh Manning (Miles Heizer) recording original songs in his college dorm room when he is interrupted by a fellow student seeking someone. Frustrated, Josh halts his session. Meanwhile, his father, Sam Manning (Billy Crudup), has just secured a major account at his advertising agency and eagerly invites Josh to celebrate after classes. Josh declines, claiming he has other obligations, but Sam insists. As Josh heads to the library instead, Sam waits at a bar, leaving a message for his son, who seems to have stood him up. Suddenly, Sam’s attention is drawn to a news report covering a tragic school shooting at Josh's campus library.
Days later, a memorial wake is held at Josh's home. His mother, Emily (Felicity Huffman), struggles to maintain normalcy amidst the media frenzy that surrounds the family's grief. With reporters cordoned off by police and helicopters hovering, Sam tries to process the loss but finds it difficult amidst the chaos. While exploring Josh's bedroom, he meets Kate Lucas (a former girlfriend of Josh) who shares memories of their past. Subsequently, Sam battles with the pressures of his professional life, succumbing to alcoholism and disrupting his job with erratic behavior, including an embarrassing incident where he kisses his receptionist inebriated.
Fast forward two years, we find Sam residing on a sailboat far removed from his previous life. He takes on a new job as a contractor's assistant while drowning his sorrows in alcohol, leading to a string of tardiness that frustrates his boss. One day while out with coworkers, he plays off his former life as a federal witness in a humorous anecdote but keeps the truth about his identity a secret. While out, he discovers that The Trill tavern has openings for musicians.
Sam’s mundane life is suddenly disrupted when Emily, mentioning she is relocating to Tulsa and divorced, shows up seeking his signature to sell their old house. She brings with her a collection of Josh's belongings: demo discs and instruments. Initially resistant, Sam ultimately decides to listen to his son’s old materials, igniting a process of healing as he grapples with Josh's legacy. Inspired, he performs "Home," one of Josh’s songs at The Trill, captivating Quentin (Anton Yelchin), a talented guitarist who is eager to collaborate with him.
As the two begin to work together, it becomes evident that Sam is hesitant to reveal the true authorship of the songs. Their collaboration blooms as they encounter other musicians, leading to regular gigs, and eventually forming a band named Rudderless. However, along the way, deep secrets about Josh’s dark past begin to surface, causing a whirlwind for Sam and the band.
As they gain local fame, Sam confronts many emotional hurdles, including a confrontation with Kate who reveals the tragic fallout from the school shooting and its impact on her life. In a moment of reckoning, Sam embraces the truth about Josh, which leads to more destructive behaviors, including a public meltdown that gets him arrested.
Over time, Sam's journey becomes one of redemption. He grapples with the reality of his son's actions, achieving a heartbreaking catharsis as he reconciles with his loss. Ultimately, he seeks to honor Josh's memory, understanding the weight of his past while bridging a new beginning for himself and Quentin, offering him a guitar as a token of encouragement to keep moving forward—one final act of homage to the music that binds them.
In a poignant climax, Sam performs a heartfelt tribute to Josh, acknowledging his true story before an audience. Seemingly renewed, he leaves the stage with both the pain of loss and the embrace of hope and closure for both himself and the band.
