My Sister is the Warrior Queen — Episode 12

Abandoned by their family, the Blackwood sisters, Catherine and Grace, had only each other to rely on growing up. As adults, both built successful lives. But at Grace's engagement party, Catherine, returning from a secret mission, showed up dressed as a cleaner, becoming the laughingstock of Grace's fiancé's family and old classmates. When her sister was betrayed and humiliated by her fiancé, Catherine revealed her true identity as the Warrior Queen, making everyone regret underestimating them.