Hardcore prosecutor Lee Tae Sung (Kim Kang Woo) takes a deep dive when he goes undercover to take down an infamous crime syndicate in Haeundae, Busan. Things are looking good for justice, up until Tae Sung loses his memory in an accident. In a turn of slapstick comedy, Tae Sung, now convinced he's a gangster, sets to terrorizing the waterfront town in true form, eventually falling for the ultimate mob princess Go Sora (Jo Yeo Jeong): a former kingpin's daughter.