Undercover High School S01E10 - Retribution

To everyone's shock, Seo Myung-joo returns to the school. Unimpressed by Hae-sung, she expels him and demonstrates her power by dismantling his team. However, refusing to back down, Hae-sung and the team, including Soo-ah and her mother, devise a daring plan to infiltrate the school once more to retrieve the hidden gold bars.