Sunny von Bülow, Glenn Close, a millionaire heiress and socialite, lies in a hospital bed in a persistent vegetative state after slipping into a coma from diabetic shock on December 21, 1980. A year earlier, she had fallen into a coma on December 26, 1979, but was revived. Her husband Claus von Bülow, Jeremy Irons, is charged with attempted murder by injecting the hypoglycemic Sunny with an overdose of insulin. During the trial, it is revealed that Claus was having an affair with actress Alexandra Isles and stood to gain financially if Sunny had died. He is found guilty on two counts of attempted murder.
While Claus von Bülow is released on bond, he files an appeal and seeks representation from Harvard law professor Alan Dershowitz. Dershowitz agrees only if Claus pays him three hundred dollars an hour, as he also works on a separate case where he tries to save two young black brothers from the electric chair. As he reviews the case, Dershowitz becomes convinced Claus is guilty based on the testimony of Maria, the von Bülows’ maid. He is given 45 days to file an appeal and assembles several of his law students to help review the details.
Dershowitz is later informed of David Marriott, a potential witness. At Marriott’s New York apartment, Marriott confesses that he worked as a drug trafficker, but Dershowitz remains skeptical about his reliability. Meanwhile, Dershowitz’s team learns that Robert Brillhoffer, the plaintiff’s attorney, had illegally withheld notes that could aid Claus’s defense. They are also alerted to a magazine interview given by Truman Capote, who stated that Sunny enjoyed mixing drugs and alcohol and taught herself how to self-inject.
Claus lunches with Dershowitz’s legal team and is questioned about Sunny’s overdose on aspirin three weeks before her second coma. Claus is unclear on what could have motivated her to suicide, but he assumes she was unhappy. After Sunny is revived from her first coma, she reprimands Claus for calling a doctor and implies that he would be better off if she had died.
Dershowitz’s defense team receives a toxicology report on the encrusted needle, which reveals no trace of insulin. Marriott arrives again at Dershowitz’s house, claiming his affidavit is not accurate. He covertly records their conversation, then edits the recording to make it look as if Dershowitz agreed to pay Marriott as a witness. Before the trial, Claus recounts what led up to Sunny’s second coma, describing how he found her lying face down on the bathroom floor with the windows open in frigid room temperature. Based on Claus’s testimony, Dershowitz believes Claus is innocent and tells his team that he will seek to overturn the conviction on grounds of insufficient evidence.
When Dershowitz dismisses his class, his students inform him that the jury reversed two convictions and they have obtained Brillhoffer’s notes. He arrives at a New York hotel suite where Claus is staying and hands him the notes, having uncovered conflicting circumstantial evidence that could exonerate Claus in his second trial. Relieved, Claus agrees to pay Dershowitz his legal fees. While Dershowitz calls it a legal victory, he delivers a blunt moral warning: > Morally, you are on your own.
Claus von Bülow is tried for a second time and acquitted, while the two young brothers remain on death row.
