Busan, South Korea, the present day. Legendary retired gangster Yoon Doo-hun (Song Kang-ho) dreams of opening a restaurant, and enrolls in a cooking class, where he gets to know Jo Se-bin (Shin Se-kyung), 20. Doo-hun then hears that his former boss, Man-gil, has died after being hit by a car; the gang's need to find Man-gil's will to see whom he nominated as his successor, though most of them expect it is Doo-hun. Meanwhile, Se-bin's roommate Lee Eun-jung (Esom) has become indebted to some Haeundae moneylenders, who force Se-bin, in return, to spy on Doo-hun. After Eun-jung steals a suitcase containing cocaine from the moneylenders, Se-bin is ordered to kill Doo-hun but can't bring herself to do it. Instead, Eun-jung tries to run him over with a car and subsequently disappears. Doo-hun survives and takes over as head of his old gang, intent on discovering who killed Man-gil. Among various problems, he has to contend with Baek Kyung-min (Lee Jong-hyuk), an ambitious young member of the gang, and his continuing relationship with Se-bin, who is under pressure from assassination agency head Madame Kang (Yoon Yeo-jeong) to kill him.