相傳，西貢的山頭上有「結界」，即類似百慕達三角的神秘異空間，令不少行山人士神秘失蹤......警長獨自行山後人間蒸發，他做社工的女兒耿耿於懷，堅持要尋找真相，但多年來苦無結果。他失蹤滿七年之際，一個瘋瘋癲癲的行山用品店主突然宣稱，他在山上的結界撿到警長的委任證！女社工沿著結界傳說追查，決心尋回父親，怪事卻接二連三發生。電影改編自過百萬瀏覽的本地網絡小說，一探香港最神秘的結界傳說。熟悉的西貢山頭和舊式公共屋邨場景，融入香港都市血案，令人不寒而慄。

In 2005, a high-profile case of a police officer who disappeared during a forest hike spawned urban legends about the existence of a gateway into another world. In 2016, those legends inspired popular internet novel Missing, which is now being adapted into an eerie supernatural thriller by first-time director and Fresh Wave alum Ronnie Chau. Former pop idol Gillian Chung stars as a social worker who hires a mountain guide to search for her missing father in the mountains. She discovers the mystical gateway from the urban legends, but is her father really waiting for her on the other side?