Season 1

Firefighter Ho Chul accidentally witnessed the crime scene of the Rich Girl Killer while on duty two years ago. He was the only witness to the murder and suffered from the trauma. In the end, he and his family moved into Parisville City, a more secure apartment. However, today in Parisville, a horrifying murder happens in the same way.

The person who kidnapped Soo A tells Ho Chul that he has 24 hours to find the serial killer and kill him. If he fails to kill him, he may see his daughter as a corpse. Panicked and worried, Ho Chul rushes to confront the ex-convict security guard he saw with Soo A to find out the identity of the mysterious man.

Ho Chul pays a severe price for going against the rules, and Dong Ju dies at the hands of Tae Jin. Ho Chul realizes that the only way he can save his daughter is to follow Tae Jin's orders. Meanwhile, the special investigation team at Hwajin Police Station begins digging into the Rich Girl serial killer case and Dong Ju's murder. As they investigate Dong Ju's murder scene, they find evidence pointing to an unexpected person.

Ho Chul gets falsely accused of the security guard's death and is a fugitive on the run. He must remember the Rich Girl Killer's face to save his daughter, Soo A. He begins to remember and starts to chase him down. Finally, he comes face to face with the serial killer.

After being held captive by Tae Jin, Soo A is now in the hands of Si Woo. Ho Chul, who is shocked and panicked, chases Si Woo down. But with Soo A at his mercy, he is powerless. In the end, Ho Chul succumbs to Si Woo's demand with his daughter's life on the line.

Ho Chul joins forces with Si Woo and betrays Tae Jin to save his daughter. Ho Chul helps Si Woo, who is holding Soo A captive, slip through the police's hands. As Si Woo escapes, he tells Ho Chul where he can find Soo A. But when he gets there, he encounters an unexpected situation.

Ho Chul witnesses Jung Hye fall into the hands of Si Woo. Ho Chul is in a complete wreck now that Tae Jin has Soo A and Si Woo has Jung Hye. Jung Hye improvises and leaves Ho Chul a clue, and he heads to rescue her. When Ho Chul gets to the location, he learns the truth behind the shocking incident.

Ho Chul rescues Soo A. However, Tae Jin and Si Woo appear together in front of them. Ho Chul and Soo A make a run for it to escape falling into their hands again. The chase is on. The four of them end back up on the rooftop of Parisville, where their goals get intertwined one last time.