The Most Plausible Theories For Who Killed Elena on 'The Undoing'

Lauren Puckett
·7 min read
Photo credit: NIKOTAVERNISE.COM - HBO
Photo credit: NIKOTAVERNISE.COM - HBO

From ELLE

Streamers would do well to keep putting Nicole Kidman in the middle of murder mysteries; she can go from doe-eyed socialite to suspected psychopath with one bat of her outrageous eyelashes. In HBO’s The Undoing, she plays Grace Fraser, whose husband (Hugh Grant) has been arrested for the murder of his mistress Elena Alves (Matilda De Angelis). But the case isn’t nearly as cut-and-dry as the police might want it to be. All the evidence points toward Jonathan Fraser, but he insists he’s innocent, and Grace has found herself smack in the middle of a few suspicious activities: namely, walking by the scene of the crime on the same night it happened. But does that mean she’s the killer?

There are a lot of fan theories—some have even started taking polls of who viewers think the murderer is—but some options seem more plausible than others as the episodes continue to roll in. Here’s how things are looking for the suspects.

Jonathan actually did it.

Perhaps the most obvious—and therefore least likely—culprit is Jonathan himself. Perhaps he’s been lying through his teeth this whole time, convincing his wife he’s innocent when, really, he’s a cold-blooded killer. The evidence does point to the disgraced doctor, and as one Reddit user pointed out, he did the fairly sociopathic deed of sleeping with his mistress, leaving, stumbling upon her dead body, and then returning to his home to…have sex with his wife, then abandon them both the next morning. That’s a little twisted. So it’s certainly possible, if not definite, that Jonathan has it in him to kill.

Photo credit: Niko Tavernise/HBO
Photo credit: Niko Tavernise/HBO

Quick spoiler: In the book The Undoing is based upon, Jean Hanff Korelitz's You Should Have Known, Jonathan is indeed the killer. But the series has made huge departures from its source material; book Jonathan never returns after he runs away. The show Jonathan seems much more nuanced—and quite possibly innocent.

Grace is the one to blame.

Another popular theory is that Grace isn’t entirely of sound mind, and she’s either accidentally or purposefully muddled up her mind to ease herself of guilt.

“If [Grace has] had 20+ years of experience as a psychologist, I think she would have learned a thing or two about reading people and situations,” one Reddit user theorized. “This strange woman started clinging to her seemingly out of nowhere. When she took the walk that was caught on camera, I think that was her heading to Elena's apartment. Grace can't remember this because she is struggling with a mental disorder herself.”

But what mental disorder? Is she suffering from dissociative episodes? And, even if she is, does she have it in her to brutally murder her husband’s mistress, especially when she seems so shocked by what’s going on around her? I think this theory makes a lot of sense, especially given a few key pieces of evidence: 1) Grace was caught on tape walking past the scene of the crime; 2) Grace had a motive for the murder, and she and Elena had a relationship; 3) She seems convinced her husband couldn’t have done it. But I also wonder if Grace’s guilt might be a little too obvious. Other psychological thrillers have played this sort of game before, giving us an unreliable protagonist who turns out to be the culprit. I worry that, if the series goes down that path, the end result will be less satisfying.

Sylvia killed Elena out of jealous fury.

When Jonathan admitted to his therapist that he’d slept with another woman besides Elena, viewers immediately started theorizing about who that might be—the mystery woman could turn out to be important. And several Reddit users are convinced his other mistress was Sylvia (Lily Rabe), Grace’s best friend.

“It also took me a bit to realize that Sylvia is the one who could absolutely be the killer and have done so in a fit of rage,” one Reddit user wrote. “She’s the one who talks about Elena’s breasts at the committee meeting, points out all the men all over her, knew TOO MUCH about Elena’s patterns at the school (“she sits out there, I saw her months ago, etc.” like she’s been watching the family for awhile), then makes a point to go out of her way to [go to] Jonathan’s arraignment. She’s my main suspect now.”

But there are a few holes in this theory. One is that Sylvia has hardly shown any signs of jealousy over Jonathan, or even particular interest in him. He’s already married to her best friend; why would she decide to kill his mistress? And why, when Jonathan needed legal help after the affair with Elena, would Sylvia be willing to help him? I like this theory because it’s unexpected, but there are one too many problems for it to be the clear winner just yet.

Franklin killed his son-in-law’s mistress.

What if the real killer is Franklin, Grace’s father? We all know Donald Sutherland is one of the best in the business at playing cruel old men. And we saw on the show just how icily vicious his character can get when threatened. Plus he has a lot of money, and therefore resources, so covering up a murder would hypothetically be easier for him than, say, Elena’s husband, Fernando. But is that enough to convict him, figuratively speaking?

Photo credit: David Giesbrecht/HBO
Photo credit: David Giesbrecht/HBO

Some fans believe Elena had another affair, this time with Franklin rather than Jonathan. When Franklin heard Elena had moved on to Jonathan, he paid someone to kill Elena and frame Jonathan for it. And perhaps Grace walked by the art studio the night of the crime because she suspected her father might have been there.

Here’s what this theory has going for it: Franklin definitely has secrets. He’s creepy enough to seem like a plausible murderer. And, if Grace really has some sort of mental disorder, she could be repressing memories of her father’s behavior.

As one Reddit user wrote: “I think that as a child, Grace witnessed or somehow knew that her father killed her mother. She repressed the memory, or he manipulated her into thinking he was innocent and good (Grace's friends are always saying she only sees good in people. This would also allow her be lied to by Jonathan and ignore his narcissism. It also kinda explains the song in the intro, that she 'dreams' about people instead of really seeing them.) Now, she witnessed Elena's murder and is similarly repressing it or refusing to believe. I also think she had an affair with Elena that she might be repressing?”

Henry’s the murderer.

Here’s where we get a little wacky—but still, technically, plausible. This theory is one of my favorites, simply because it’d be the most shocking. And as the end of last week's episode showed, it's certainly plausible.

Up until that point, Henry seemed like nothing but a sweet, innocent young boy. But keep in mind that, when he visited his father in prison, they appeared to pass something. A note, perhaps? And all those scenes emphasizing Henry’s violin practice—we now know he was hiding the murder weapon in the violin case. Did he help Jonathan conceal the evidence? Or, perhaps, he was so furious at his father for cheating, he went and killed his mistress.

One Reddit user explained: “I think Henry is the killer and he’s getting his psychopathic behavior not from his father but from his mom. She witnessed her dad’s affairs, killed one of his mistresses and buried that knowledge under the false story of her parents’ perfect marriage.” Another fan added, “The scene where Henry apologizes to Elena’s son (for apparently 'bumping into him') could also feed into this theory as he could be apologizing for murdering his mother.”

But such an act is horrible in and of itself, let alone if it were committed by a young boy. Would HBO be willing to take such a risk?

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