Spoiler alert: Do not read if you haven’t seen the finale of “The Undoing”.

Sunday’s “The Undoing” finale answered the question viewers have been asking for weeks: Who killed Elena Alves?

The most likely suspect ended up being the person responsible for the character’s death… something fans of the show weren’t expecting.

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In the latest twist in last week’s episode, Grace Fraser (Nicole Kidman) discovered a mallet — the potential murder weapon — hidden in her son Henry’s (Noah Jupe) violin case.

It’s then revealed that the 12-year-old was trying to cover up a murder he thought his father Jonathan Fraser (Hugh Grant) had committed.

And it turned out Jonathan, who was arrested for Elena’s murder on episode 2 of the six-part series, was, in fact, guilty.

RELATED: Hugh Grant Jokes He Did ‘The Undoing’ To ‘Get Away From My Young Children’

Social media users, including celebs Kelsea Ballerini and Megyn Kelly, were left in shock by the much-talked-about conclusion.

See some of the reaction below.

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