Pei Yu is an easygoing young man who gets by on a constant stream of cheeky banter. In truth, he has extraordinary powers of deduction, though he always pretends to be clueless. Three years ago, his friend Chen Xiao stabbed him in the back, leaving him with amnesia. When Pei Yu woke up, a five-year-old bundle of joy named Pei Xiaosuan was by his side, claiming to be his son and possessing an astonishing talent for mathematics and observation. Pei Yu discovers he has gained a golden finger: “Causal Deduction,” which lets him work backward from scraps of information to uncover the truth. To find out what really happened back then, he and his son plunge into a battle of wits over an inheritance worth tens of billions. He jokes and flirts on the surface while laying trap after trap in secret. When all the evidence points to Chen Xiao, a misunderstanding leads Pei Yu to believe the boy isn't his biological son. Breaking down, he confesses his heartfelt love to the child: “Whether or not we're related by blood, you're the most important thing in my life.” In the end, the truth comes to light, and father and son join forces to outwit the villains so thoroughly they question their sanity.
