Tang Chuan (Wang Kai), a physics genius who works at the Criminal Police Academy, and Shi Hong (Zhang Luyi), a middle school teacher, met each other when they were young and appreciated each other because of their common interest in mathematics. Many years later, when Tang Chuan was investigating a murder case, Chen Jing (Ruby Lin), Shi Hong's neighbor, was listed as a "suspect" by the police. Shi Hong and Tang Chuan met again, but Tang Chuan discovered a bigger secret during the investigation... Tang Chuan and Shi Hong, who were forced to stand on opposite sides, started a high-IQ duel, which pushed the story step by step towards a shocking and regrettable ending.