Ryan Gosling as Jacob Palmer
Steve Carell as Cal Weaver
Julianne Moore as Emily Weaver
Emma Stone as Hannah Weaver
Analeigh Tipton as Jessica Riley
Jonah Bobo as Robbie Weaver
Marisa Tomei as Kate Tafferty
Kevin Bacon as David Lindhagen
Cal Weaver is a middle-aged man who learns that his wife Emily cheated on him with a coworker, David Lindhagen, and wants a divorce. After moving into his own apartment, Cal goes to a bar night after night, talking loudly about his divorce, until he attracts the attention of a young man named Jacob Palmer who is a womanizer who beds women each night, although a young woman named Hannah recently had rejected his advances. Jacob takes pity on Cal, and agrees to teach him how to pick up women. Using Jacob's teachings, Cal seduces Kate at the bar. After this encounter, Cal manages to successfully seduce other women in the bar.
He sees Emily again at his son Robbie's parent-teacher conference. The meeting goes well until they discover Robbie's teacher is Kate, who reveals to Emily that she and Cal slept together. Emily leaves in disgust and begins actively dating David.
Meanwhile, Hannah, a recent law school graduate, is expecting her boyfriend, to propose marriage while they celebrate her passing the bar exam, but he does not, which hurts Hannah's feelings. Hannah returns to the bar where she originally rejected Jacob's advances and kisses Jacob passionately. The two return to Jacob's home to have sex, but end up talking to each other all night and making a connection. Jacob starts a relationship with Hannah, and he becomes distant from Cal.
At the same time, Robbie makes numerous grand gestures to try to win the heart of his 17-year-old babysitter, Jessica Riley, who actually has a crush on Cal. On the advice of her classmate Madison, she takes naked photos of herself to send to Cal and tucks them away in an envelope inside her dresser drawer.
Later, when Emily calls Cal under the guise of needing help with the house's pilot light, Cal decides to try and win her back. Meanwhile, Jacob returns Cal's calls and asks for advice about starting a real relationship.Jessica's mother discovers Jessica's naked photos addressed to Cal in her drawer and shows them to Jessica's father. He rushes to the Weaver residence to confront him about the photos.What will happen at the Weaver’s now????