Ben (Ng Chun-yu) is the producer of a Hong Kong radio program called "Horror Hotline," and he has been neglecting his girlfriend Helen (Zhou Liqi) due to his busy work. Helen is a nurse who secretly had an abortion, which she struggles to come to terms with, often seeing visions. Mavis (He Chaoying) is a reporter for an American television news network, and along with her crew of five, she arrives in Hong Kong to shoot a special program about the local radio culture, with their first research subject being "Horror Hotline." However, Ben is not friendly and only allows them to film outside the studio. One night, the host of "Horror Hotline" receives a call from a man identifying himself as Chris, who claims that in 1963, while playing football with six classmates in the Western District, they stumbled upon a "big-headed monster baby" in a nearby cave, which scared them terribly; even the principal, who is a Muslim, could not subdue it with the Quran in his hands. Chris's call unexpectedly generates a strong response, leading both Ben and Mavis to decide to investigate it further, though they have different journalistic approaches. At almost the same time, the hospital where Helen works admits a traumatized teenager named Sam (Li Can-sheng), to whom Helen does not respond like she does with...