Flailing at life, Lee Tang panics after he kills a man after work. Soon, Jang Nan-gam is on the case — discovering a disturbing truth about the victim.

A mysterious woman approaches Tang, claiming to know his secret and begins to blackmail him. The weight of his actions starts taking a mental toll.

Nan-gam struggles to find clear answers as he investigates the latest deaths. After connecting with an enigmatic figure, Tang decides to turn himself in.

Wondering if the same killer is behind all the murders, Nan-gam probes Roh Bin for clues, leading to an unlikely partnership between the two.