Big Bet follows the turbulent life of Cha Mu-sik, a man who rises from a poverty-stricken childhood to become the legendary king of the casino world in the Philippines. Through sheer grit, intelligence, and a lack of moral hesitation, he builds a massive gambling empire, navigating the dangerous intersections of organized crime, local politics, and high-stakes business dealings. However, his ascent is challenged when he becomes entangled in a murder case, drawing the attention of Oh Seung-hoon, a diligent Korean police officer dispatched to the Philippines to investigate. As the net tightens around him, Mu-sik must navigate a web of betrayal, shifting loyalties, and the consequences of his past actions, leading to a desperate, high-stakes gamble for his own survival.