Dr. Alan Feinstone has everything. A beautiful wife, a nice house, a dentist, a popular reputation and is obsessed with order and cleanliness. However, everything changes. On the day of his wedding anniversary, he spies his wife Brooke having sex with their filthy poolman, Matt. Feinstone waits for them to finish, retrieves his handgun (a .380 Walther PPK) and then follows Matt in his car.
        He's led to Paula Roberts's house, a friend of Brooke's. Hiding the gun behind his back, he quickly makes up a story about inviting Paula to a surprise party for Brooke. He then sneaks into her backyard in time to see Paula invite Matt inside. Paula's dog, a rottweiler, emerges from the yard and attacks Feinstone. He shoots the dog through the head and proceeds to drive to work.
        At his dental practice, Feinstone's first patient of the day is young Jody Sanders, there for his very first dental appointment. Feinstone begins to clean Jody's teeth. Everything goes smoothly at first, until he imagines that Jody's teeth are brown and rotten. His dental pick slips, stabbing Jody in the gums. Jody's mother picks up her crying, bleeding child and leaves angrily.
        As Feinstone sees his second patient, beauty queen April Reign, Detective Gibbs investigates the death of Paula's dog. He suspects the perpetrator was the burglar who has been robbing houses in the neighborhood, though that criminal has never used a gun before.
        Alone with April, Feinstone sedates her with nitrous oxide so that he can fill a cavity in one of her molars. As she drifts off into unconsciousness, Feinstone imagines that she has transformed into his wife. He begins kissing and fondling his "wife" on the dental chair, then begins to choke her. April starts to cough and half-wakes up from the gas. Feinstone snaps out of his trance and quickly re-buttons April's blouse and finishes removing her pantyhose. Hiding the pantyhose behind a counter, Feinstone helps the still-coughing April into the arms of her manager, Steve Landers. He leads them out claiming April is dizzy from the nitrous oxide. Steve returns a few minutes later and punches Feinstone hard in the mouth. They leave angrily, threatening a lawsuit on their way out. Feinstone decides to end the day early and sends his staff and patients home. Especially disappointed is Sarah, a teenager who desperately wants to get her braces removed. Feinstone's friendly office manager, Candy, tells her that she'll have to wait until tomorrow.
        Later that night, Brooke meets Feinstone at his practice. He reveals his new Italian opera-themed patient room. He encourages Brooke to try out the room's dental chair and clean her teeth. When she does, Feinstone binds her to the chair with a scarf and sedates her with nitrous oxide. With operatic music blaring in the background, he begins to pull out Brooke's teeth and cuts out her tongue.
        Investigating the burglaries, Detective Gibbs and his partner Detective Sunshine arrive at Feinstone's door the next morning to ask