Park Avenue dentist Norm Goldman leads a double life, and has two distinct dental practices to show for it. While his high-end clientele bore and agitate him, he is much more comfortable working on the teeth of the children of Harlem. But Doctor Goldman has a secret habit that spans both practices. He is a nitrous addict. After walking his receptionist, Mimi, to the train stop, the doctor is ready for his fix. Sitting back and enjoying a blissed-out high in his Harlem clinic, Goldman is too limp to fight off the killer standing over him.
Though initial suspicions by Goldman's wife, Moira, are levied against the local population, the dentist was loved and embraced by the Harlem community. Goren spots a man, Roy, whose close proximity to the clinic makes him an obvious choice for a good eye witness. Roy, appreciative that Goren doesn't bust him for selling illegal subway swipes, tells the detective that he saw a woman, then two teen boys leaving the clinic the night of the murder. When suspicious activity turns up on Goldman's credit card, Goren and Eames zero in on the two teen boys. Selling sneakers in a park, the detectives bust the kids for stealing Goldman's card. Pressured by Goren and Eames, the boy holding the money spills that he stole the card, but only after Goldman was already dead. Like Roy, he reports that he saw an unstable lady leaving the clinic and suspects she may be the dentist's killer. But the boy's mother gives the detectives an unexpected motive for Goldman's murder: the good doctor was a suspected pedophile.
Perhaps Doctor Goldman was not so revered and respected after all. Upon reviewing Goldman's appointments with Mimi, the detectives learn that many of his patients cancelled appointments with the dentist after a flu outbreak in a local housing project. One of the children, Toby Boren, has just died. After his grieving mother hurls a glass at the front door and screams at Eames, the detectives tentatively approach her apartment. As they enter, Mrs. Borden, in a fit of rage, pulls a knife to her daughter's throat. Goren plays Mrs. Borden's psychotic game and manages to calm her down long enough to get her daughter safely away. In doing so, Goren squeezes her for a confession of murder. She killed Goldman, claiming that the dentist got his child patients drunk, then molested them. When authorities didn't do anything about it, she took matters into her own hands. Goren suspects that the sick children are suffering from alcohol poisoning, and he thinks that mouthwash in the dentist's goody bag for his patients may be the culprit.
When the detectives interview a child in the hospital with symptoms of alcohol poisoning, the boy reveals that Dr. Goldman had nothing to do with it. It was their idea. Three other kids drank the mouthwash, in the hope of getting buzzed. Unfortunately for the children, Toby's tox screen reveals that he did not die of alcohol poisoning, but in fact was killed by a lethal amount of Diethylene glycol, or DEG, in his system. Now that the detectives know the culprit, they realize that the FDA may have had a hand in these deaths. Had there been a recall of the defective mouthwash, these tragedies may never have occurred.
Goren and Eames interview Bing Schoor, CEO of Schoor Labs, makers of SnoMint mouthwash. Also present are Leslie LeZard, and her FDA Director boss, Mary Palin. It is revealed that, in fact, a counterfeit version of SnoMint is the actual culprit and the executives promise to inspect the shelves and pull all the contaminated products from the stores. However, an eager FDA inspector, Jim Kettle, has already been working tirelessly to do just that. Clearly, someone has dropped the ball, and there has been some sort of cover-up. Jim had threatened to shut down a mom-and-pop bodega if the owner, Cho, didn't get rid of the counterfeit mouthwash. But some boxes fell through the cracks, and he donated them to Goldman's dental practice for a tax write-off. Unfortunately, these donated boxes were responsible for the deaths of the children. When Jim's body turns up dead, killed by a defective asthma inhaler from Schoor Labs, the detectives begin to further suspect the big Wall Street corporation and the FDA. Jim was making too much noise for someone's liking.
When an incriminating inter-office memo is slipped to Goren by LeZard, the detectives delve deeper into the cover-up. She implicates her boss, Marty Palin, and Bing Schoor, in the murder of Jim Kettle. But when Stacey, a suspected mole within the organization, points the detectives back to LeZard, Goren and Eames start to scrutinize her work history and career ambitions. LeZard had lied about attending Yale, amongst other things. But though she is a life-long career fabulist, there is no reason to suspect her of murder. However, using her immense career aspirations and craftiness against her, Goren and Eames expose LeZard's scheme: she killed Jim Kettle, framed her boss, and positioned herself as a whistleblower. In an effort to rise to the top of her field, LeZard's "know-no-bounds ambition" ruined the lives of many.