Asura: The City of Madness (2016)

Detective Han Do Kyeong, who for years has been secretly doing dirty work for the corrupt mayor Park Seong Bae, is now pressured by a ruthless prosecutor Kim Cha In to cooperate in an investigation against the mayor. Feeling trapped, Han persuades his young partner Moon Seon Mo to take over his work for the mayor, but things start to get tangled in unpredictable ways. As things are getting worse, only the most evil survives in this dog-eat-dog world.