HBO's The Undoing: One Theory That Star Lily Rabe Doesn't Buy Into At All

Spoilers below for the final episode of HBO's The Undoing, so be warned!

Across its first five episodes, HBO's killer thriller The Undoing inspired fan theories the way rain inspires wetness, and the speculation was aimed at everything from Donald Sutherland's eyebrows to young Miguel's sleeping patterns to the trustworthiness of Jonathan's mother. One character who seemingly sparked more theories than any other beyond Nicole Kidman's Grace was Lily Rabe's Sylvia, who always seemed to know just a little bit more than she was letting on. Rabe enjoyed being at the center of such guesswork, but there's one theory that she just can't get behind.

One of the most prevalent ideas about Sylva is that she was the "other woman" that Hugh Grant's Jonathan confessed to having an affair with – even though we all know that dude likely had a longer line of lovers during his marriage with Grace – and American Horror Story vet Lily Rabe understands that idea. But she drew the line when it came to the theory that Sylvia was actually Jonathan's sister that hadn't actually died in that horrible traffic accident when Jonathan was 14. Here's how Rabe laughingly put it to TVLine:

That one is new to me. . . . Wait, that I'm Jonathan's sister? Hmmm, I don't know about that one. The rest of them I can [get on board with]. That one is really a stretch though.

Had Sylvia actually been Jonathan's sister, that would have thrown a really weird wrench into the works, and it's hard to consider exactly what ramifications it would have. In the first place, it would make Jonathan look shitty for again lying about his childhood trauma. (In his original story, it was a dog that died.) In the second place, it would have indeed made the mom out to be a total liar during her talk with Grace. In the third place, the sister being alive would somewhat account for Jonathan's lack of remorse or trauma after her supposed death all those years ago, and if that story didn't come up during the trial, then Jonathan might indeed have been later acquitted. Not to mention her helping Jonathan despite his affair, and her being Grace's bestie. Too many weird details to work around there.

For what it's worth, Lily Rabe doesn't think all of The Undoing's theories are as batshit crazy as that. In fact, she's rather into the idea that her character was secretly working with Donald Sutherland's Franklin. Here's how she put it:

I knew about the affair with Jonathan. I also knew that there was a theory that Franklin and I were in cahoots — which I liked. Sylvia has known Franklin since she was born; their families summered together. And I think they had a bond and a likeness of spirit. We sort of imagined that during those summers when everyone went to bed they were probably the last two that stayed out late finishing the second bottle of wine.

One can imagine that Franklin and Sylvia shared some wild conversations at Jonathan's expense over the years, and I wouldn't be too surprised if she'd divulged the confession about Jonathan to him long before she told Grace. Everybody wants Donald Sutherland on their side.

Creator David E. Kelley also spoke out about the Sylvia theories when asked, telling TVLine the following:

We were inviting people to play with their biases and their curiosity and their version of the truth. There were scenes with Sylvia that were deliberately cryptic, but it was never part of the master plan to have her be part of the crime. I’m not on social media, but I was hearing that some people speculated that Franklin was having a relationship with her or Jonathan was having a relationship with her. And when I go back and look at the episodes I make room for the possibility that people might fill in some of those blanks and arrive at those conclusions. But it was never part of the plot.

Of course, all that guessing and suspecting was for naught in the end, and the main thing Sylvia was "guilty" of was intentionally helping the prosecution by sharing the story of Jonathan's sister, with Grace's approval of course. Oh, and I guess she is also to blame for cluing viewers in on the show's finale right there in the series premiere, as evidenced below:

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Always the husband indeed. The Undoing doesn't currently have any plans to go forward with a second season, but the ratings have been pretty solid, so we'll just have to wait and see if HBO orders any more up. In the meantime, head to our Fall 2020 TV premiere schedule and our Winter and Spring 2021 TV guide to see everything that's hitting the small screen soon.

Nick Venable
Assistant Managing Editor

Nick is a Cajun Country native, and is often asked why he doesn't sound like that's the case. His love for his wife and daughters is almost equaled by his love of gasp-for-breath laughter and gasp-for-breath horror. A lifetime spent in the vicinity of a television screen led to his current dream job, as well as his knowledge of too many TV themes and ad jingles.