Still single seven years after the breakup of his marriage, John (John C. Reilly) has all but given up on romance. But at the urging of his ex-wife and best friend Jamie (Catherine Keener), John grudgingly agrees to join her and her fiancé Tim (Matt Walsh) at a party. To his and everyone else's surprise, he actually manages to meet someone: the gorgeous and spirited Molly (Marisa Tomei).
Their chemistry is immediate. The relationship takes off quickly but Molly is oddly reluctant to take the relationship beyond John's house. Perplexed, he follows her home and discovers the other man in Molly's life: her son, Cyrus (Jonah Hill). A 21-year-old new age musician, Cyrus is his mom's best friend and shares an unconventional relationship with her. Cyrus will go to any lengths to protect Molly and is definitely not ready to share her with anyone, especially John. Before long, the two are locked in a battle of wits for the woman they both loveand it appears only one man can be left standing when it's over.