In an affluent suburb of Chicago, Illinois, high school senior Joel Goodsen is eager to lose his virginity, but worries that an upsurge in his social life might distract him from his studies. Aside from his preoccupation with sex, Joel is obsessed with getting into a good college to study business and secure a lucrative career. Joel’s promiscuous friend, Miles, encourages the boy to have a party while his parents are out of town, claiming the event will provide an opportunity for Joel to have sex. However, Joel is hesitant to defy his parents, and, after dropping them off at the airport, he celebrates his independence by dancing around the living room in his underwear. Sometime later, Miles comes by the house to chide Joel for his lack of sexual initiative and browses newspaper advertisements for a prostitute. Despite Joel’s protests, Miles makes an appointment, and a transvestite named “Jackie” arrives at Joel’s doorstep. Although Joel turns her away, Jackie demands payment before leaving and gives the boy a telephone number for “Lana,” assuring him that the young woman will fulfill his desires. Plagued by sexual dreams, Joel finally telephones Lana, who comes to his house for an evening of lovemaking. Observing the opulence of Joel’s home in the light of day, Lana demands a $300 fee, but he does not have enough money and leaves the house to cash a bank bond. When Joel returns, he finds Lana missing and realizes the girl has stolen the centerpiece of the living room mantle, his mother’s beloved crystal egg. Joel telephones Jackie for advice, steals his father’s sports car, and tracks Lana down at an upscale hotel, where she slips into the vehicle and orders him to drive away because she is in trouble with Guido, her “manager.” Joel refuses to help until Lana returns the egg, but Guido wields a gun and they speed off, with Guido in pursuit. Joel gets away and returns home with Lana, who spends another night in his bed. When Joel prepares for school in the morning, Lana convinces him to let her stay home alone and vows to procure the egg once she retrieves her belongings from Guido. While Joel attends classes, Lana rifles through the Goodsen house for valuables and invites her fellow prostitute, Vicki, to join her. When Joel comes back, he is relieved to discover his home intact, but irritated that Vicki has “serviced” one of his friends. Although she offers Joel a commission, he has no desire to become a pimp and orders the girls to leave. As they walk away, Guido arrives and they run back inside, claiming Joel is their new boss. Guido warns he will return to get revenge and Joel grudgingly allows the girls to stay until morning. Despite Joel’s attempts to focus on homework, he is lured out on a date with Lana, and they drive to the shore of Lake Michigan to smoke marijuana and eat ice cream. Noting Joel’s interest in free enterprise, Lana proposes a business partnership in which she supplies prostitutes for Joel’s wealthy friends for one night, while his parents are still out of town. In return, Lana promises to share the profits and be Joel’s girl friend for the weekend, free of charge. When Joel declines, Lana grabs her pocketbook from the sports car to leave, but she accidentally shifts the car into gear, and walks away as it rolls toward the lake with Joel clinging to the hood. The boy believes he has successfully stalled the car on a pier, but the wood buckles, and the vehicle plunges into the lake. After spending the night at a car dealership and learning of the prohibitive repair cost, Joel arrives late for school and is unable to convince the nurse that he deserves an excused absence. Losing his composure, Joel threatens the nurse and his outburst results in suspension. With nothing more to lose, Joel agrees to Lana’s business plan, hoping they will gross enough earnings to fix his father’s car. Lana returns the crystal egg in good faith. Preparing for the party, Joel hones his skills as a salesman and convinces his classmates that a one-time investment in a professional sex worker is more cost-effective than paying for repeated dates with reluctant schoolgirls. The event is overflowing with customers and Joel basks in his success, but he fails to remember an interview that evening with Bill Rutherford from Princeton University. After an awkward meeting, in which Rutherford is perplexed by Joel’s enterprise, the gentleman enjoys the services of several ladies. Joel is convinced he has lost his opportunity to attend an Ivy League school, but Lana reminds Joel that he is already a prosperous businessman, raking in cash while providing a valuable service. To celebrate, Lana invites Joel to make love on a train and they ride the subway all night. The next morning, Joel retrieves his father’s repaired sports car and prepares for his parents’ homecoming, but he discovers the Goodsen house was stripped of its belongings while he was on the train with Lana. When Joel telephones the girl in a panic, Guido picks up the phone, declares that he has the furniture, and arrives at the Goodson home with a packed moving truck. As Joel’s parents ride home from the airport in a taxi, Joel buys back their possessions with his remaining profits from the party. The final object in the truck is the crystal egg, but Joel has only $40 left and Guido wavers at the low price. However, he agrees to sell it back on condition that Joel be indebted for a future payment. Guido’s prostitute, Vicki, who has returned to help with the sale, throws the egg across the lawn, and Joel catches it in just in time. With his friends, Joel reassembles the house and his parents return home to find everything in its place, although his mother is outraged to find a tiny crack in her egg. Joel believes he is finally in the clear, but his father receives a telephone call from Bill Rutherford, the Princeton recruiter. Bracing himself for condemnation, Joel is surprised to learn his entrepreneurial efforts have been rewarded with admission to the university. Joel celebrates with Lana, who has returned to prostitution, and asks if she lured him onto the train so Guido could rob his house. Lana claims innocence and propositions Joel for one last night of sex before they part ways. Reassured that their affair was not just business, after all, Joel playfully asks Lana if she can afford his services.