456 people, most of whom are experiencing serious financial problems, accept an invitation to participate in a mysterious tournament of children's games. It quickly becomes apparent that this is a survival tournament. After a player is eliminated from the competition, the prize money increases by 100 million won, meaning the winner of the tournament will receive 45.6 billion won (at the time of the series' creation, this is equivalent to 38.5 million US dollars). However, the stakes in the games are deadly high.