With different goals in mind, Lee Eun and Hong Deok Su step into Yongcheonru as interns. On their first day, they are connected through a mysterious golden key, leading to an unforeseen turn of events.

Lee Eun keeps a close eye on Deok Su, who possesses the golden key, waiting for the right moment, while Deok Su grows more cautious, noticing Eun's suspicious looks. Meanwhile, a murder case involving a fake Hongpae shakes Yongcheonru, raising the tension even higher.

The "However 4" are fighting hard to pass their test, but Choi Sang Bang is scheming to kick them out. Meanwhile, Lee Eun Ho watches Deok Su closely to check for the golden key, but this makes others start to doubt who Eun Ho really is.