Raised by an older brother who was a genius gambler and learned countless tricks of the trade, the man known as "Bull" knows every kind of cheat. However, he himself has never used any of them—he lives a regular life as a full-time office worker. Then one day, his brother goes missing. As Bull searches for him, he uncovers a clue: his brother has fallen into "the Swamp," a deadly gambling den where those consumed by greed end up.