Barry Egan is a bachelor who owns a company that markets themed toilet plungers and other novelty items. He has seven overbearing sisters who regularly ridicule and emotionally abuse him, so he leads a lonely life punctuated by fits of rage and social anxiety. One day, he witnesses an inexplicable car accident, picks up an abandoned harmonium from the street, and meets Lena Leonard (a coworker of Elizabeth, one of his sisters). Lena had orchestrated the meeting after seeing him in Elizabeth's family picture at work.
Barry goes to his sister's birthday party, where they tease him about his sexuality, leading to a serious outburst in which he breaks all sliding glass doors. Afterwards, he asks his brother-in-law to refer him to a therapist. Instead, Barry calls a phone sex line to cope with his loneliness. The phone sex operator tries to extort money from him and then sends four henchmen, who are brothers, to collect. This complicates his budding relationship with Lena, as well as his plan to exploit a loophole in a Healthy Choice promotion and amass a million frequent-flyer miles by purchasing large quantities of pudding.
When Lena leaves for Hawaii on a business trip, Barry decides to follow her, using his sister to find Lena, who is overjoyed to see him. As the two spend time together, Barry's sister calls Lena, complicating matters, but Lena lies about having contact with Barry. The romance develops further, leading to Barry's relief from his emotional isolation.
On the return trip, the four brothers ram Barry's car, mildly injuring Lena. After fighting the brothers off with a tire iron, Barry leaves Lena at the hospital and sets out to end the harassment. He calls the phone-sex line back and finds out the "supervisor" is the owner of a mattress store. Barry drives all the way to Provo, Utah, to confront the owner, Dean, face to face. At first, trying to intimidate Barry, Dean finds him more intimidating once he learns that Barry has come all the way from California. They both agree "that's that".
Barry returns home and goes to see Lena to explain why the accident happened. He begs for forgiveness, pledging his loyalty and to use his frequent-flier miles to accompany her on all future business trips after his pudding miles are processed. Lena confesses she was more upset at being left at the hospital, but forgives him and they embrace happily.
