In the past, Seongho had participated in various programs run by the orphanage and the church.  

The classes, often led by volunteers, were some of the most prominent.  

Seongho used to frequent the cultural school building, almost as if it were his second home, due to these classes.  

Then, one day, Seongho made an astonishing discovery in the school building.  

He saw that a steel door leading to a deep underground passage was open.  

To make matters worse, a flashlight was left right beside the door.  

*‘Someone must have briefly left the facility during …