Season 1

With his very existence teetering on the brink, Cha-il barely escapes death and uncovers the treacherous rat hiding within JU Construction. Faced with no margin for error, Cha-il devises a daring and impeccable strategy to ensnare the rat. Every move must be executed with precision, for even the slightest misstep could unravel the entire plan and spell disaster for them all.

Following the death of former president Gun-woong, JU Construction is entering a transitional phase where new leadership will soon be established. In the midst of this uncertainty, Cha-il uncovers a massive corruption scandal within the company. As he investigates further, he discovers that the corruption is deeply entrenched within the core of the organization. Cha-il vows to wage a battle against the primary culprit exploiting the company.

The audit team successfully tracks down the employee who joined the company through improper means, only to be shocked when an unexpected culprit is revealed. Meanwhile, Cha-il's aggressive auditing methods draw unwanted attention and place him under scrutiny. As the audit on Cha-il progresses, the team uncovers new information about his past.

Although Han-soo's injustice gets resolved through Moon Sang-ho's involvement, this time, a photo of Dae-woong and Seo-jin together gives rise to the unfair hiring issue that has been dying down. Se-woong takes this opportunity to take down Dae-woong and orders Cha-il to audit the case. When Cha-il reports without results, Se-woong rejects it and hires an external audit team to take over.

Cha-il successfully identifies the criminal responsible for the technology leak during the preview. However, an unexpected turn of events causes even greater damage to JU Construction. As the situation spirals out of control, Se-woong's position within the company becomes increasingly precarious. Before the leak incident can be resolved, another issue arises concerning unfair hiring practices at JU Construction, with some familiar faces potentially at the center of this controversy.

Han-soo learns the shocking details of Yoon-woo's self-immolation attempt and starts to suspect that Mr. Park might be trying to leak J-BIMS technology. With the sneak preview event just around the corner, Se-woong has ordered that no disturbances occur before the preview, leading to a suspension of the investigation. Despite this, Cha-il's keen intuition brings him closer to uncovering truths that others have overlooked.

Cha-il narrows down the suspects and eventually tracks down the food poisoning culprit. Meanwhile, Se-woong, the current president of JU Construction, becomes sensitive due to the upcoming demonstration of J-BIMS, a project he worked hard to achieve. Amidst the affairs, Yoon-woo from the research department attempts to set himself on fire in the lobby of JU Construction.

A letter exposing the corruption behind the on-site restaurants arrives at Cha-il's desk, and a food poisoning case arises at the shopping mall construction site's on-site restaurant. After urgently shutting down the JU Construction cafeteria and on-site restaurants, the Audit Team investigates corruption behind the selection process of the on-site restaurants. However, the Audit Team struggles to find clear evidence and faces Da-woong's opposition.

Cha-il tells Dae-woong that he will take responsibility and recover the embezzled money, but Dae-woong gives Cha-il an absurd condition for his promise. He tells him if he doesn't recover the money, he will have to resign and pay back the missing 3.4 million dollars. However, Cha-il still accepts the condition. Meanwhile, the Audit Team locates the money and arrives at its location.

Cha-il investigates a 3.4-million-dollars embezzlement case from a housing project and investigates Mi-kyung, the head of the Housing Team, who is his college junior. As the investigation progresses, a sexual harassment scandal occurs between them, putting the embezzlement case in turmoil. However, when Cha-il thinks he's solved the case, Hwang Dae-woong stands in his way.

Cha Il investigates Senior Managing Director Seo and VP Hwang, but evidence gets tampered. He focuses on the tower crane operator's role on the accident day, uncovering anomalies.

Shin Cha Il becomes the new head of JU Construction's Audit Team. He reopens an investigation into a tower crane accident, suspecting corruption. At the construction site, he discovers incriminating evidence on the foreman's laptop.