Park Hae-young continues to try catching the culprit that kidnapped his childhood schoolmate and after that they began a small police force which solved outdated unsolved cases and they are starting on a popular serial killer case.
Park Hae Yeong and Cha Soo Hyun are waiting for the DNA results of the corpse they found. Meanwhile, they remember Lee Jae Han. Hae Young discovers that he was never alone, and Soo Hyun remembers the last time she saw her sunbae and her 15-year waiting for their reunion.
Following the trail the Section Chief left, Park Hae Young uncovers the truth behind his brother's death. Meanwhile, Cha Soo Hyun finds Lee Jae Han's radio in Hae Young's possession.
Park Hae Young is framed and arrested for the murder of the Section Chief. Cha Soo Hyun sets out to save Lee Jae Han and to find the one witness who can bring down their enemy.
Lee Jae Han is set on bringing down Kim Bum Joo, despite knowing that he's going to die, but a certain transmission is about to make all the difference.