Dan Mulligan, portrayed by Mark Ruffalo, is a former record label executive based in New York City who finds himself in a tough spot—both personally and professionally. Estranged from his wife Miriam and increasingly disconnected from his teenage daughter Violet, he grapples with the shifting tides of the music industry, desperately searching for the next big talent that he can help launch to stardom. Over the past five years, Dan has struggled to find an artist worth his while, with Troublegum, a rapper discovered by him, being his last major success.
While at work, Dan shares a bold idea with his business partner Saul: music, in his view, should be free. Unfortunately, this sentiment does not align with Saul's vision of rapid commercialization. Following his dismissal from the label, Dan attempts to bond with Violet over drinks, yet his lack of funds and failed attempts to borrow money lead to him getting punched by a bartender, resulting in Violet walking away in disappointment.
In a haze of alcohol, Dan stumbles into a bar on the Lower East Side, where he encounters Gretta James, played by Keira Knightley, a passionate British singer-songwriter performing her own music. Gretta, recently heartbroken after splitting from her former boyfriend and songwriting partner, Dave Kohl—played by Adam Levine—is adjusting to life post-breakup. Her relationship with Dave, who has had a meteoric rise in the music scene, was fraught with creative differences; he often pushed her to modify her raw melodies for broader appeal.
With the support of her only friend in the U.S., Steve, Gretta is vulnerable yet resilient. Captivated by her talent, Dan offers her a contract with his former label, but after some hesitation, she reevaluates her options and decides to accept his proposal. In a candid moment, Dan shares how Gretta’s song compelled him to reconsider ending his life, revealing his unique ability to envision musical arrangements that complement an artist's voice.
As their collaboration blossoms, Dan sees potential in transforming Gretta's image, suggesting a more polished look akin to Norah Jones. Although Gretta is eager to return to England, Dan persuades her to delay her flight by another day, allowing them to further explore their creative partnership. After presenting Gretta to Saul, whose feedback is lukewarm, Dan suggests a bold plan: to record an album live at various public venues throughout New York City, forging ahead even without Saul’s endorsement.
As work progresses on the album, Dan and Gretta develop a deeper bond, with Gretta also taking the opportunity to mentor Violet, portrayed by Hailee Steinfeld, instilling confidence in her as a budding guitarist. The narrative takes a poignant turn when Gretta sees Dave accepting an award on television, prompting her to express her feelings about his artistic compromise through a song recorded on his voicemail. Dave, filled with remorse, reaches out, leading to an emotional confrontation where Gretta critiques him for straying from their original artistic vision.
When their album is complete, Dan and Gretta once again meet with Saul, who is surprisingly impressed with their work, leading Gretta to demand Dan's reinstatement at the label and a more considerable stake in their deal. Though they leave without an agreement, Dan remains optimistic about Gretta's prospects. Their interactions culminate at Dave’s concert, where Gretta witnesses firsthand his divergence from the essence of her song, ultimately deciding to distance herself from him for good.
Later, Gretta visits Dan as he prepares to return to his family and reconciles with his wife. In a twist, she reveals her wish not to pursue a traditional release for her album but rather to sell it online for $1. Dan supports her decision, helping to promote the album's release. Remarkably, Saul later jokingly "fires" Dan after discovering the album sold 10,000 copies on its first day, a clear testament to Dan’s enduring talent for connecting with audiences, marking a new beginning for both him and Gretta as they navigate the complex waters of the music industry together.
