<Korean TV Series NOW> ”Undercover High School” EP2, Seo Kang Joon is in danger while investigating the mystery of the old building = Viewership rating 6.6%, Synopsis / Spoilers

*This article contains spoilers. In EP2 of the MBC TV series "Undercover High School" (viewership rating: 5.8%), Heso was exploring the first floor of the old school building.
The episode depicted Soo Ah (Seo Kang Joon) facing a crisis. Hye Sung shined her flashlight on Soo Ah (Jin Ki Joo) and then ran away, somehow managing to escape the situation.
When Hye-sung saw the principal, Jae-moon (Park Jin-woo), descending to the basement of the old building, she felt suspicious. Hye-sung also heard a ghost story going around the school from Dong-min (Shin Jun-han).
A while ago, a girl who was bullied by other students took her own life in a classroom in the old building, and since then, the dead woman and her friend have been appearing in the closed practice room at the same time every day. Dongmin doesn't believe in ghost stories.
He shocked Hye-sung by showing her the video he had taken himself. Hye-sung went to the old building to uncover the truth behind the ghost story, where she happened to meet Dong-min and he decided to accompany her. The two of them entered the building, but where did they go?
They hear classical music and descend into the basement where they find a mysterious man hammering a hammer, but when the two appear, he throws it away and runs away.
After a while, we entered the basement, where we found the first director of the Seo family (Kim Ui-seong) and a treasure chest of Emperor Gojong's gold.
Newspaper clippings cover the walls, suggesting that the chairman, Myung-ju (Kim Shin-Rock), is also searching for gold.