Ben Campbell is a young, highly intelligent student at M.I.T. who strives to succeed. Wanting a scholarship to transfer to Harvard School of Medicine to become a doctor, Ben learns that he cannot afford the $300,000 tuition as he comes from a poor, working-class background. But one evening, Ben is introduced by his unorthodox math professor to a small but secretive club of five students, Jill, Choi, Kianna, and Fisher, who are being trained by Professor Rosa to count cards at blackjack. Inspired by real events and people, 21 is about six MIT students who become trained to be experts in card counting in Black Jack and subsequently took Vegas casinos for millions in winnings.