One spring morning in Shermer, Illinois, teenager Ferris Bueller feigns illness to stay home from school. As Tom and Katie Bueller dote over their impish son, Ferris’s younger sister, Jeanie, is enraged by the ruse and vows revenge. With the family gone, Ferris sunbathes and telephones his best friend, Cameron Frye, who is perpetually sick and absent from school. Ferris plans to cure Cameron’s depression with a carefree adventure, but Cameron is averse to getting out of bed and drives to Ferris’s house only grudgingly. Elsewhere, Katie Bueller receives a telephone call at her office from Edward R. “Ed” Rooney, dean of students at Shermer High School. The principal complains about Ferris’s poor attendance and threatens to forestall the boy’s upcoming graduation, but Katie does not believe her son is a truant. When Principal Rooney looks at his computer record for evidence, he notices Ferris’s nine absent days dwindle down to one and realizes the boy is manipulating his student file from home. Enraged, Rooney fears the student body will imitate Ferris’s shenanigans. He pledges to find Ferris and shame him in front of his classmates, but students are already bustling with rumors and concern about Ferris’s presumed illness. Meanwhile, Ferris continues to plot his self-appointed day off by fraudulently excusing his girl friend, Sloane Peterson, from class. Ferris convinces Cameron to phone school in the guise of Sloane’s father and announce the unexpected death of her grandmother. Taking the call, Principal Rooney suspects he is speaking to Ferris, not “Mr. Peterson,” and demands to see the grandmother’s corpse before Sloane leaves campus. Just then, Ferris telephones Rooney’s office on another line and Rooney recoils, now believing he has actually insulted the real Mr. Peterson. Continuing to impersonate “Mr. Peterson,” Cameron gets carried away with the prank and orders Rooney to escort Sloane outside. Since Ferris must now masquerade as “Mr. Peterson” in person, he convinces Cameron to “borrow” his father’s prized possession, a 1961 Ferrari 250 GT California. Cameron is terrified of his volatile father and hides under the sports car’s retracted convertible roof as Ferris collects Sloane from school. As the three friends speed toward downtown Chicago, Illinois, Principal Rooney realizes he has been outwitted and sets upon an ill-fated mission for revenge. Ferris leaves the Ferrari with an unsavory parking attendant and coerces his way into a fancy restaurant, where he narrowly misses crossing paths with his father. The friends attend a Chicago Cubs baseball game at Wrigley Field, and Ferris catches a stray ball. After visiting the Art Institute of Chicago, the threesome come across the General Von Steuben German-American Appreciation Day Parade. Ferris energizes the crowd with lip-synched versions of the songs “Danke Schoen” and “Twist And Shout.” Back in Shermer, Principal Rooney hunts Ferris and breaks into the Bueller residence. Ferris’s sister, Jeanie, continues her own pursuit of Ferris and returns home to discover a strange man lurking in the kitchen. Unaware the intruder is Principal Rooney, Jeanie kicks him unconscious and telephones police. However, the operator believes Jeanie is giving a fraudulent report and the girl is detained at the police station for making a “phony” call. Jeanie seethes with anger as she waits for her mother, but she is seduced by a handsome drug addict with whom she shares a waiting room bench and the encounter makes her less embittered. Meanwhile, Principal Rooney awakens in the Bueller kitchen and staggers outside as his car is towed away. In Chicago, Ferris and his friends return to the parking garage and are relieved to find the Ferrari seemingly unharmed. On the way home, however, Ferris notices the odometer reading is over 150 miles in excess of when they began their adventure and Cameron becomes catatonic. Ferris drives to Sloane’s house, where they attempt to rouse Cameron by luring him into the jacuzzi, but the boy remains listless. As Cameron sits in a deck chair, perched at the edge of the diving board, he plunges head first into the pool. Ferris fears his friend has attempted suicide, and dives in the water to save him. When the boys resurface, Cameron is unresponsive and Ferris panics. However, Cameron revives with a smile, revealing that he staged the incident to quell Ferris’s sense of invincibility. The threesome drive back to Cameron’s house, immobilize the Ferrari with a jack, and run the car in reverse to restore its original mileage. While the vehicle churns in its glass-walled garage, Cameron describes the catatonic spell in which he observed life from afar. He declares that he is no longer depressed and credits Ferris’s antics as the inspiration for his spiritual awakening. He refers to Ferris’s “day off” as “the best day of my life.” Sloane points out that Cameron’s spirits may also have been lifted when he caught a glimpse of her naked body at the pool. When Cameron realizes the Ferrari’s mileage is not corrected, he refuses to be intimidated by his father and kicks the sports car in anger, inadvertently causing it to reverse through a glass wall. The Ferrari plummets into a ravine. Although Ferris offers to take the blame, Cameron relishes the opportunity to challenge his father and sends his friends home. Ferris escorts Sloane to her house and bids her farewell with a kiss, but rushes away when he realizes his parents will be home in five minutes. As Ferris darts across the street, he nearly collides with the Bueller family station wagon, driven by Jeanie, who is taking their mother home from the police station. Jeanie stares at Ferris through the windshield and speeds away in the hope she will get to the house first and finally expose Ferris’s high jinks. Although Ferris makes it back before his sister, he is intercepted by Principal Rooney, who threatens to punish him with another year of high school. Just then, Jeanie discovers Rooney’s wallet on the kitchen floor and realizes he was the intruder. Redirecting her rage at the principal, Jeanie appears at the back door and plays along with Ferris. As Ferris darts back to his bedroom, Jeanie hands Rooney his wallet with a stern warning and the principal skulks away. Ferris survives the pitfalls of his day off unscathed, and remains infallible in the eyes of his oblivious parents.