The series revolves around a contest where 456 players, all of whom are in deep financial debt, risk their lives to play a series of deadly children's games for the chance to win a billion prize. Inside, a tempting prize awaits with deadly high stakes.The title of the series draws from a similarly named Korean children's game. Hwang had conceived of the idea based on his own economic struggles early in life, as well as the class disparity in South Korea and capitalism.