In the ‘90s in Taiwan, two students share one desk at a high school divided into day and night classes. It is a story of love, friendship, disappointments, and ultimate growth bolstered by a compelling cast of up-and-coming Taiwanese acting talents.

Fisherman Ah-Hai is found dead from self-immolation during a large-scale protest against TL Petrochemical. The incident instantly makes media headlines; Ah-Hai is hailed as a martyr. Medical examiner Chou is assigned to the case with public prosecutor Kim, his ex-fiancée. When the two discover evidence of murder and a major conspiracy, Chou breaks protocol to conduct his own investigation in order to protect Kim. As the truth is gradually revealed, the case and their past start to intertwine...

阿南是个镇日处在虚拟世界里生活的动画宅，他疯狂迷恋动画「波比达」。他与妈妈及失智爷爷同住，向来平静的生活在落魄的叔叔带着女友搬回家之后改变了，一家人时时处在对立状况。阿南迷恋上了一位同样喜欢波比达动画的女孩，他为了标下女孩最想要的世上仅有一套的波比达特摄人偶，到处借钱打工。一天，他意外发现爷爷存折里有一大笔钱，眼看美梦就要实现，却没想到让自己惹上许多麻烦，甚至引来杀机。 导演表示，《最乖巧的杀人犯》这部作品最想说的是人与人的关系，「家庭」是社会中最小的单位，爱与血缘无关，常常住在一起的人，其嫌隙可能比不常在一起的人更加巨大。同一个屋檐下，人来人去，大家却是那么疏远。我想呈现的是一个支离破碎的家庭中的状况，并没有什么大道理，却是真实台湾社会中的家庭状况。也透过虚构的动漫角色波比达与男主角之间的伙伴情谊，剖析媒体对于动漫次文化见猎剥削的现象，本片却试图让一桩本是刻板的社会事件还原出真实人事物，探究这背后的人心欲望、认同渴望及家庭关系等等的省思。