After eight months’ treatment in a mental health facility for bipolar disorder, Patrizio “Pat” Solitano Jr. (Bradley Cooper) is released into the care of his father Patrizio Sr. (Robert De Niro) and mother Dolores (Jacki Weaver) at his childhood home in Upper Darby, Pennsylvania. His main focus is to reconcile with his ex-wife, Nikki (Brea Bee). She has moved away and obtained a restraining order against him after Pat found her in the shower with another man and badly beat him. During his time in the clinic Pat befriends Danny McDaniels (Chris Tucker), an easygoing man who is embroiled in a legal dispute with the clinic on whether or not he is eligible to leave. Pat’s therapist, Dr. Patel (Anupam Kher), does his best to convince him to keep taking his medication, as a repeat of his violent outbursts might send him back to the clinic. But Pat tells him that he has a new outlook on life: he attempts to see the good, or silver linings, in all that he experiences. Patrizio employs the Latin phrase “Excelsior,” translated as “always higher” or “ever upward,” as the mantra of his new optimistic outlook. Meanwhile, Pat experiences a series of anxiety attacks in his new life, including a violent reaction to Ernest Hemingway’s A Farewell to Arms, which he throws into the yard, destroying his bedroom window in the process.
At dinner with his friend Ronnie (John Ortiz) and Ronnie’s wife Veronica (Julia Stiles), Pat meets Veronica’s sister Tiffany Maxwell (Jennifer Lawrence), a young widow with an unnamed disorder. They connect over dinner talking about different drugs they have taken to manage their mental illnesses. Sparks fly between Pat and Tiffany and she tries to connect by offering casual sex, but Pat keeps focusing on getting Nikki back. Tiffany tries to get closer to Pat and even offers to deliver a letter to Nikki—if, in return, he will practice dancing (which she does as a therapy) with her and partner with her in an upcoming dance competition. He reluctantly agrees and the two begin a rigorous practice regimen over the following weeks. Even Danny comes to help, but when he does Pat starts to get jealous of Tiffany and shows her a bit of affection but tries to push it away. Pat believes the competition will be a good way to show Nikki that he has changed and become a better person.
The elder Patrizio hopes to open his own restaurant and has resorted to illegal bookmaking. Having bet virtually all of his money on the outcome of a Philadelphia Eagles game, he asks Pat to attend as a “good-luck charm”. Pat asks Tiffany for time off from practice to attend the game. She gives him a typed reply from Nikki, in which she cautiously hints there may be a chance for reconciliation between them. Before he gets into the stadium, Pat and his brother Jake get involved in a fight when some racist fans harass a group of Indian fans that happen to include his therapist, Dr. Patel, and is hauled away by the police. The Eagles lose the game and Patrizio is furious. Tiffany shows up at their house and points out that the way she is “reading the signs,” Philadelphia teams do better when she and Pat are together. Convinced, Patrizio makes a parlay with his gambling friend Randy: if the Eagles win their next game and Tiffany and Pat score 5 out of 10 in their dance competition, he will win back double the money he lost on the first bet. Pat is reluctant, and Tiffany, Dolores, and Patrizio conspire to persuade Pat to dance in the competition by telling him that Nikki will be there; it is revealed that his parents have secretly supported Tiffany’s attempts to get along with him. Pat notices that the letter from Nikki also refers to “reading the signs” and realizes that Tiffany wrote it.
Tiffany, Pat, and their friends and family arrive at the competition on the night of the football game. Tiffany despairs when she finds that Nikki actually is in the audience, invited by Ronnie and Veronica, who want Nikki to lift her restraining order on Pat and give Pat the chance to reconcile with her. Tiffany walks to the bar and starts drinking. Pat finds her moments before their dance and drags her onto the dance floor. They begin their routine as the Eagles defeat the Dallas Cowboys. At the conclusion of their set, Tiffany and Pat receive an average score of exactly 5.0 points. Amid cheers from friends and family and confused looks from the crowd, Pat approaches Nikki and speaks quietly into her ear. Tiffany sees this and runs off. Pat leaves Nikki behind after a short conversation, and chases Tiffany. He hands her a letter, in which he admits that he knows she forged Nikki’s letter and confesses that he loved her from the moment he met her, though it took him so long to come to terms with it. They share a kiss. Patrizio opens a restaurant with the money he has won, Danny grows even closer to the Solitanos, and Pat and Tiffany begin a relationship, no longer wearing their wedding rings.