靈感源自2000年紐約駭人案件，17歲香港少女找來黑人男友謀殺自己雙親。憑《音樂人生》奪得香港電影金像獎新晉導演獎的張經緯首部劇情長片，把泯滅人性的事件分拆重組，移至最被遺忘的北區角落，再加入探員的視點，對比出中產、底層兩種永不相容的生活。無情的階級，冷漠的命運，將一殺一救的二人無形地繫在一起。電影不囿於懸疑類型的框架，細膩呈現血腥之下的壓抑心理；層層剖析殺戮背後的痛苦宿命，入木三分、發人深省，拍出獨有風格。

A pregnant policewoman is assigned to investigate the case of a teenage girl who has killed her parents. Her interactions with the girl and the search for the truth revive a long-dormant secret that has been living inside of her. Best known for acclaimed documentaries KJ and The Taste of Youth, director Cheung King-wai presents a much darker side of today’s troubled youth with his first feature-length dramatic narrative film. Loosely based on a true story, this grim and engrossing whydunit is a disturbing shocker about redemption, fate, and the lengths we go in our constant search of a better life.