Choi Mu-gak agrees to help Oh Cho-rim with her comedy skit in exchange for assistance on a case that could earn him a spot in the Violent Crimes Unit.

Cho-rim leads Mu-gak to a body in the river, and is later followed. Mu-gak reveals to Cho-rim how he lost his sense of pain, taste and smell.

A new barcoded body is found, but Lt. Yeom Mi suspects it's a copycat killer's work. An accidental injury brings Cho-rim to Dr. Cheon Baek-gyeong.

When a strangled chef falls off a roof, Kwon Jae-hui becomes a suspect, but a scent leads Cho-rim elsewhere. Mu-gak learns why Baek-gyeong went to Jeju.

A confession letter is written and stored. Ju Ma-ri's journals are discovered. Mu-gak figures out what the barcodes on the victims' bodies signify.

The Barcode Killer places the next body so it will be found, and covers his tracks. Cho-rim's friend Ma Ae-ri is accused of stealing from her employer.

Mu-gak is rushed to the hospital, where the police set a trap for his attacker. The Barcode Killer decodes his last victim's cryptic final message.

Mu-gak lures the Barcode Killer using fake medical records and a decoy Choi Eun-seol. Yeom Mi creates a police sketch of the woman Cho-rim remembers.

Yeom Mi follows her hunch about Cho-rim, who has a flashback to the moment of her accident. The misplaced confession letter is found among some books.

Mu-gak snoops in Yeom Mi's office and learns why she took him off the case. The Barcode Killer visits Cho-rim's dad to find out who the witness is.

Cho-rim manages to escape from the Barcode killer, who steals a photo from her father's home address in order to identify her.

Cho-rim reveals her special ability to the entire Violent Crimes Unit. The Barcode Killer uses the witness's old school friends to lure her into a trap.

When the police are unable to find the secret room where Yeom Mi is being held, Cho-rim contacts the Barcode Killer and volunteers to take her place.

The Barcode Killer makes a run for it. Cho-rim remembers more about her parents and the day of her accident. A romantic gesture backfires on Mu-gak.

The Barcode Killer abducts Cho-rim in order to lure Mu-gak into a deadly trap, but Cho-rim leaves behind a clue that could save his life.