When Yeong-jae gets accepted into a top medical school, his mom becomes the envy of the other mothers, who all want to know just how she managed it.

Han Seo-jin confronts the entrance exam coordinator. Lee Su-im joins the Sky Castle reading group, but it’s nothing like what she expected it to be.

Sky Castle is abuzz about the pending vote but Cha Min-hyeok is confident. Seo-jin will do anything for Ye-seo – and stoop as low as deemed necessary.

Seo-jin runs into Yeong-jae and tries to talk to him. Su-im ponders what to do about Ye-bin. No Seung-hye and Min-hyeok scramble to formulate a plan B.

Seung-hye challenges Min-hyeok head on. Seo-jin thinks that she’s fixed things but doesn’t count on Kang Jun-sang. Ye-bin finds an unlikely confidante.

Su-im and Ye-bin are stunned by what they uncover. Seung-hye and Su-im speculate about Yeong-jae and his family. Kim Ju-yeong puts Ye-seo in her place.

Running mates Kim Hye-na and Hwang U-ju are the favorites in the school election, but Seo-jin colludes with Min-hyeok to ensure that their kids win.

Kang Jun-sang delights in Seo-jin’s plan to host a dinner as an occasion to gloat over the other couples, but things get heated over Su-im’s new book.

Seo-jin incenses Kim Ju-yeong with her reply, and leads the charge against Su-im, but pays a heavy price for her shortsightedness in more ways than one.

Seo-jin relents and has Hye-na move in as Ye-bin’s tutor, but makes a startling discovery. Su-im meets Yeong-jae’s father to get his side of the story.

Su-im hears a strange fact about Kim Ju-yeong. Seo-jin’s fury boils over. Min-hyeok basks in his daughter’s stories, but Seung-hye spots something odd.

Crushed by the truth about Se-ri’s life in Cambridge, Seung-hye fears the repercussions of Min-hyeok finding out. Su-im gets a request from Yeong-jae.

Seo-jin lambastes Kim Ju-yeong but realizes she’s no match for her own daughter’s insolence. Seung-hye reflects on her choices and takes a stand.

Hye-na is rushed to the hospital, but Jun-sang orders Hwang Chi-yeong to operate on another patient. Seo-jin asks Ye-seo what she did at the party.

Not caring if U-ju is sacrificed, Seo-jin begs Kim Ju-yeong to save her daughter, but Ye-seo insists he’s innocent. Su-im infers a sinister motive.

Jun-sang reproaches Seo-jin and his mother about Hye-na. Seo-jin has harsh words for Kim Ju-yeong but has only one thing on her mind: Ye-seo’s future.

Jun-sang wants to go to the police and exonerate U-ju, but Seo-jin won’t let him. Seung-hye doesn’t want to live with Min-hyeok – and the kids concur.

Su-im pleads with Seo-jin, who remains determined. Ye-bin tells her mother what she thinks of her. U-ju wants to know why he should forgive Seo-jin.

U-ju announces he’s taking a break from school. Jun-sang resigns and Seo-jin readies to leave Sky Castle. Seung-hye prevails and Su-im’s book comes out.