Chinese adaption of the Japanese novel of the same name written by famous thriller writer, Higashino Keigo.
SHI Hong (Zhang) is a highly talented maths teacher, who lives next door to a divorced single mother, Chen Jin (Ruby Lin) and her daughter. One day Chen accidentally kills her abusive ex-husband who shows up to extort money. Overhearing the accident, Shi, who has a secret crush on Chen, offers his help, disposing of the body and plotting the cover-up of the murder step-by-step. After the body turns up and identified, the police come to Tang Chuan (Wang), a genius physicist and college friend of Shi, for help to solve the mythical case and the intellectual duel between the two old friends begins.