Emily tries a series of SSRI anti-depressant medications, but none of them work. Jonathan contacts Emily's previous psychiatrist, Victoria, who suggests that Jonathan put Emily on a new drug called Ablixa. Jonathan is reluctant to put Emily on the experimental drug until she attempts suicide a second time by trying to jump onto a subway track. The medication works, enabling Emily to function normally besides occasional sleepwalking episodes, a side effect of the drug. One evening, she stabs Martin to death while seemingly sleepwalking.

Emily is brought to trial, and Jonathan fights for her acquittal. He is criticized publicly for fumbling Emily's case, and his colleagues assume he has been negligent due to his heavy work-load. Emily eventually agrees to plead insanity; she is declared not guilty on the condition that she stay in a mental institution until cleared by a psychiatrist.

Due to the case's bad publicity, Jonathan's career is left in ruins. However, he sets out to clear his name and uncovers evidence that not only did Emily fake her suicide attempts, but was involved in a criminal conspiracy with Victoria. Jonathan interviews Emily after administering what he claims is a truth serum. Emily behaves as if she's groggy from the drug, which unbeknownst to her is actually a placebo. This confirms Jonathan's suspicions.

When Jonathan confronts Victoria with his findings, she mails photographs to Jonathan's wife implying he had an affair with Emily; Jonathan's wife and steps on leave him. Jonathan manages to turn Emily and Victoria against each other by using legal means to prevent contact between them and making each believe that her partner had sold her out to Jonathan for a better deal.

Emily reveals the workings of the plot to Jonathan: she enjoyed the rich life and hated Martin for causing her to lose it. She specifically went to Victoria for counseling as she, too, had been abandoned by her husband, and the two began a romantic and sexual relationship. They taught each other about the workings of the financial world and faking psychiatric disorders. They then went to elaborate means to fake the side effects of Ablixa in order to manipulate the stock prices of the drug's manufacturer and its competitor, allowing the duo to become rich in the process.

Jonathan agrees to release Emily from the psychiatric ward under his care. Wearing a wire, she immediately re-unites with Victoria, who admits details of the plot to Emily. Victoria is arrested for conspiracy to commit murder, but Emily, due to double jeopardy, can no longer be held criminally responsible for her part in Martin's murder.

As retaliation for Emily's part in the plot, Jonathan, who still technically oversees her case, prescribes her a series of unnecessary drugs with serious side effects, threatening to send her back to the ward if she refuses. Furious, Emily rants about all that she has done to avoid being sent to prison for Martin's death. Unbeknownst to her, Martin's mother, her lawyer, and a police officer are all outside the room and hear the confession. The police take Emily into custody and send her back to the mental ward.

In the final scene, Jonathan has regained his normal life with his wife and step son. Emily sits in the ward, staring blankly out the window. A psychiatric nurse asks Emily how she's feeling, and she responds by saying apathetically: "Better. Much Better."