The janitor Yong-mi overhears Tae-kyung's secret phone call as he engages in insider trading; faced with a once-in-a-lifetime opportunity, Yong-mi takes a step into the back-alley of the financial markets for a chance at a "normal life."

Soo-ja behaves differently from Yong-mi's expectations; Yong-mi and In-kyung use the information they obtained after the twists and turns to invest in stocks for the first time in their lives.

As things get worse, In-kyung and Yong-mi decide to leave Bestid to find new jobs; Yongmi comes in danger of losing his own children; Yong-mi decides to learn the name of the 3D printer company to bring his children back.

Yong-mi feels undecided between the two companies; In-kyung accidentally receives Tae-kyung's project call; Yong-mi hides her identity and attends an insider meeting; an unexpected person appears.

Yongmi's heart almost explodes after an unexpected meeting; Yong-mi escapes the crisis on his own terms at the insider meeting; Yong-mi, In-kyung and Su-ja plot to infiltrate the Ilwon Foundation to obtain more information.

Having successfully completed their first joint operation, Yong-mi, In-kyung, and Su-ja celebrate, but shadows of the past begin to fall on Yong-mi.