The noir / crime drama revolves around the love and struggles of undercover agents and members of an infamous drug ring. When her older sister Lee Kyung-mi is murdered while undercover in the criminal underworld, Yoon Soo-min is driven to pick up where Kyung-mi left off. But in the shadows, there are no rules and no reason; Soo-min falls for the organization's drug kingpin, "The Doctor's Son", who also happens to be the prime suspect in her sister's murder.
Cast
Main
Jung Kyung-ho as Jung Shi-hyun - Grew up in a red light district / brothel until his mom died from drug-overdose. Then ran away from an orphanage and eventually became a drug courier for "Uncle" Safari. Shi-hyun is nicknamed "The Doctor's Son" and became the boss of a mid-sized gang. Highly ambitious. He is plotting to take over the position of "Scale", his drug supplier.
Lee Jae-yoon as Ji Hyung-min - Hyung-min graduated from the police academy with top scores and gets promoted at a young age. Was studying law to join the Prosecutor's office, but returned to the police force to avenge an undercover officer's death. Now the section chief of a special investigation unit, his goal is to take down "Scale", which leads him to Shi-hyun.
Nam Gyu-ri as Yoon Soo-min - Soo-min grew up in an orphanage with Kyung-mi, and they treat each other like real sisters. When Kyung-mi is killed in the line of duty, Soo-min goes undercover to catch her friend's killer and finish what Kyung-mi started. However, she ends up falling for "The Doctor's Son", the drug lord Kyung-mi was investigating until her untimely death.
Son Chang-min as Min Hong-ki, Director of the police / special investigative unit.
Kim Yoo-mi as Lee Jin-sook, President / CEO for various adult entertainment establishments. Worked the streets at a younger age. Close friend to Shi-hyun's mom. Looked out for Shi-hyun as he was growing up. Along with Soo, they both support and follow Shi-hyun's direction / quest to take over the drug distribution channel.
Choi Moo-sung as Moon Deok-bae - Knew Shi-hyun as a child. Paths did not cross again until he was sent down to Busan to pursue "Doctor's Son". Taught / gave Shi-hyun a switchblade knife when he was younger.
Yoon Hyun-min as Kim Hyun-soo - Met Shi-hyun in prison and both worked under "Halibut". At times, hot headed but loyal to a fault.
Supporting
Go Na-eun as Lee Kyung-mi, an undercover agent. She is Hyung-min's girlfriend and Soo-min's older sister. She grew up with Shi-hyun at the orphanage and is hinted that she is Shi-hyun's love interest, she later on died after being shot in the head by a sniper during an undercover mission to catch "Doctor's Son" who happened to be Shi-hyun.
The soundtrack digital single "Hurt" was sung by Kim Yong-jin of pop group Bohemian. Its repetition every episode followed the dark noir theme of the series.
International broadcast
It aired in Vietnam on HTV2 from August 4, 2015, under the title Sống trong tội ác.
It aired in Thailand on MONO Plus from March 5 to May 8, 2016, under the title Fị rạk meụ̄xng khæ̂n.
