Jung-O lives with her single mother and her father has ignored her existence. After graduating from college, Jung-O struggles to find a job. One day, she decides to take an exam to become a police officer. She studies for 2 years and finally passes the exam. Jung-O enters the police academy. There, she meets fellow cadet Sang-Soo. Sang-Soo has a mother and an older brother. He worked as an intern at a water company. He wanted to become a full time employee there and worked incredibly hard, even buying stock in the company. Sang-Soo was devastated to learn that the company was a fraud. He saw a notice announcing an exam to become a police officer. He decided then to become a police officer.