Set against the backdrop of the 1940s, 'Decoded' follows Rong Jinzhen, an autistic mathematical genius with an extraordinary gift for numbers. Recruited by Unit 701—a secretive, elite Chinese cryptanalysis agency—Rong is tasked with cracking 'Purple', a notoriously difficult enemy cipher code that threatens national security. As he navigates the high-stakes world of espionage, betrayal, and psychological warfare, Rong must transform from a socially isolated eccentric into a vital secret agent, supported and challenged by his fellow operatives and mentors.