On the Verge of Insanity Season 1

Hanmyeong Electronics undergoes a mass layoff of their workers. However, for Mr. Choi Ban Seok, he gets assigned to the Changin Business Department. Although his experience and expertise in electrical appliances land him a desk job, he opts to keep working with his hands. He arrives at Hanmyeong Electronics Changin Campus for his first day of work, where he meets Han Se Gwon, his team leader.

Ja Young arrives at Hanmyeong Electronics in Changin and smacks Se Gwon across his head for sending Ban Seok to work in HR when he has no experience in the field. Meanwhile, Ban Seok finds out that Se Gwon had secretly switched a part in the vacuum robot to pin the malfunction on him. Nevertheless, Ban Seok tries working in HR even without Ja Young's support.

Ban Seok convinces Ja Young that he will learn HR's ropes and makes it on the team. However, his first task puts him in front of Han Se Gwon, an unbearable person for him to be questioning. Meanwhile, the team leader of the Motor Team, Kang Min Goo, sexually harasses a woman in the company and refuses to apologize.

Ban Seok finds himself in a blackmail and sabotage scheme between Han Se Gwon, No Byung Guk, and Kang Min Goo, but it ends up backfiring on him. With his neck on the line, he thoroughly investigates to get to the bottom of things and proves his credibility. Meanwhile, Ja Young tries to figure out how to save two valuable members of the Motor Team from resigning.

Ja Young gets faced with the difficult task of reducing Changin Business Department employees by 40 percent. Without a way of knowing who to keep and who to let go, she proposes a company-wide job adequacy test to come up with a list. Meanwhile, everyone at Hamyeong Electronics scrambles to create a project proposal and asks Ban Seok for his help.

Ja Young earnestly asks Ban Seok for his help regarding the job adequacy test. She even gives him her personal credit card to sway his colleagues who have made this into a company vote. Meanwhile, a senior researcher speaks her mind when she gets humiliated by Se Gwon, who had stolen her proposal and left her out of the Task Force Team.

After hearing about Ja Young's reason for her being in Changin, Na Ri and Se Gwon talk behind her back that Ja Young overhears. Shortly after, Na Ri and Se Gwan see in astonishment Ja Young's drunken sudden lunge toward Ban Seok, who had been waiting for her. Later, Ja Young has to face Ban Seok to fire him, overcoming the awkwardness due to what happened the night before. However, she thinks of another way.

Ban Seok starts working on the new product. However, when he looks to change the main chip, he finds evidence of corruption in the bidding process for the component manufacturer, QK Korea, and reports it to Ji Young. Meanwhile, Se Gwon messes up his presentation to the company's president and risks losing the Home Workout Mirror project.

Se Gwon tells Ja Young that he tampered with the temperature of the main chip in the dishwashers, and she notices there are complaints from the users online. Millions of dishwashers are already sold, and she can't either report it or let it slide since the disposal is just around the corner. Meanwhile, Ban Seok is suspicious of Ja Young as she is excessively involved in the Research and Developments matters when she is the team leader of Human Resources.

Ja Young decides to tell the truth about the defect in the dishwasher to President Han right before the product demonstration. For a backup plan, Ja Young asks Ban Seok to present the new system he created as a countermeasure for the defective dishwasher. Now that President Han knows about the defect in the products, he orders an investigation to take disciplinary measures at the headquarters.

Ban Seok continues to work hard on the Malfunction Identifying System, trying to secure the next chapter in his life. However, the company puts into action its personnel reduction plan. As Ja Young reviews a list of recommended candidates for voluntary retirement, she sees Ban Seok's name. Meanwhile, the senior employees are appalled at the policy and try to find a way to survive, especially Ban Seok.

Ban Seok gets pushed to the extreme and resorts to blowing up the company's dishwasher at his house. Ja Young rushes to stop him, but Ban Seok's mental state is far worse than she had imagined. While Ban Seok threatens to take her down and the company, an unexpected visitor flusters Ja Young in her current situation.

Ja Young suddenly finds herself as the newest member of the Product Planning Team. Ban Seok strongly encourages her to quickly find a different job since she doesn't know anything about development or its basic terms. However, even while dealing with her sick father, she determines to push through. Meanwhile, Se Gwon returns as the team leader for the Product R and D team and clashes heads with Ban Seok once again.

Se Gwon's return puts everyone in discomfort. Right off the bat, he makes it his priority to torment Ban Seok by putting an impossible task to his Malfunction Identifying System. However, Ban Seok doesn't stop and pushes ahead. Meanwhile, Se Gwon seems to be up to no good, making a suspicious deal with Hanmyeong E and C.

The Home Workout Mirror demonstration passes with flying colors, and everyone thinks it's a success. However, the evaluation report states otherwise, putting the whole company in peril. Meanwhile, Se Gwon hands in his letter of resignation and plans to work for Hanmyeong E and C just as he had planned.

To Ban Seok's surprise, Ja Young and Na Ri join his company. Now a force to be reckoned with, they gear up for a presentation in front of Se Gwon, who is now part of Hanmyeong E and C, and hope he finds DS Doctor worthy of their Fitness Mirror. They wait for his reply anxiously. However, Hanmyeong Electronics steps in, putting the whole deal in jeopardy.