My Sister Is the War Queen — Episode 20

Abandoned by their parents, the Blackwood sisters grew up relying only on each other, both building successful lives as adults. However, at Grace's engagement party, Catherine arrives straight from an undercover mission, still dressed as a janitor, and becomes the laughingstock of the in-laws and former classmates. But when Grace is betrayed and humiliated by her own fiancé, Catherine reveals her true identity as the legendary War Queen, making everyone regret ever underestimating them.