Asura: The City of Madness (2016) online

Detective Han (JUNG Woo-sung), who for years has been secretly doing dirty work for the corrupt mayor Park Sungbae (HWANG Jung-min), is now pressured by a ruthless prosecutor Kim Cha-in (KWAK Do-won) to cooperate in an investigation against the mayor. Feeling trapped, Han persuades his young partner Sunmo (JU Ji-hoon) 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.