Since the finale of The Undoing, there have been mixed reactions from viewers who weren’t satisfied by the reveal of Elena Alves’ killer. Well, The Undoing‘s book ending and the difference between the novel and the show may explain why Jonathan Fraser had to be the one to kill Elena.

The Undoing, which premiered on HBO in October 2020, was based on Jean Hanff Korelitz’s 2014 book, You Should Have Known. The show stars Nicole Kidman as Grace Fraser, a psychologist whose husband, Jonathan Fraser (Hugh Grant), is accused of killing Elena Alves, Jonathan’s mistress and a mother at the New York City private school that the Frasers’ son, Henry, also attends. After six episodes of a whodunnit mystery, The Undoing revealed in its finale that Jonathan did in fact kill Elena out of fear that Elena will ruin his family. For many viewers, the ending was too obvious and not satisfying enough, given that Jonathan was the main (and only) suspect in the miniseries. Here’s why the book does a better job at explaining why Jonathan is the killer.

Image: Courtesy of Grand Central Publishing.

In the book, Grace is not only a psychologist, but the author of a forthcoming book also titled You Should Have Known. The book is a self-help guide for couples centered on the main piece of advice that Grace gives her clients: They should known if someone is bad for them from the first time they meet. The book is about how people should trust their instincts and not ignore red flags when it comes to relationships. The book also mirrors Grace’s relationship with Jonathan and how she didn’t know many secrets that he had but should have. Those secrets include Jonathan’s firing from the hospital he worked at, him accidentally killing his sibling when he was a kid (in the book, it’s a brother. But in The Undoing it’s a sister.) and, of course, him killing Elena, whose name is Malaga in the book.

But the book (both Korelitz’s and Grace’s) also mirrors the journey of the reader, as they read You Should Have Known. In the end of the book, Grace learns that Jonathan killed Malaga when she receives a letter from Jonathan at her family’s home in Connecticut, which she moved to after she and Henry fled New York. In the letter, Jonathan confesses to killing Malaga and tells Grace that he’s fled the country and hopes that she can forgive him and they can reunite. Like the show, Jonathan explains in the letter that he killed Malaga because he feared that she would ruin his family. Jonathan also asks Grace not to tell the police about his letter. In the end, once Grace realized what she should have known all along (that Jonathan was a killer who wrecked her family), she gives the letter to the police, who use it to track Jonathan. The ending is also a wink to the reader, in how they should have known Jonathan was killer all along, given the many clues that were red flags and not red herrings. The show, however, eliminates all that by changing the title and making Grace simply a psychologist.

Another difference in the book is that the reader never meets Jonathan. By the time the mystery starts, he’s long gone, which leads to suspicion over whether he’s also dead and killed by the same person that murdered Malaga. While neither The Undoing or You Should Have Known is perfect, the book does a better job at explaining why Jonathan had to be Elena’s killer.

The Undoing is available to stream on HBO Max. You Should Have Known by Jean Hanff Korelitz is available on Amazon.

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