Three years after taking down a synthetic drug syndicate, Ma Seok Do's (Ma Dong Seok) new mission involves chasing down criminals who deal drugs through a delivery app. When one of the app's workers is found dead in the Philippines, the team's investigation reveals that his death is linked to a complex web of online gambling and cryptocurrency schemes. The mastermind behind it all? Ex-special forces mercenary Baek Chang Gi (Kim Mu Yeol), who aims to monopolize Korea’s illegal online gambling business in the Philippines by any means necessary, while his accomplice, IT genius Chang Dong Cheol (Lee Dong Hwi), plans to launch a massive cryptocurrency scam. Needing a way in, Detective Ma teams up with prior adversary Jang I Su (Park Ji Hwan), a former gangster and casino owner, to try and dismantle the criminal network – but is Detective Ma in over his head? This is the fourth installment in the "Crime City" series, following "The Roundup: No Way Out."