Hong Kong, the present day. At the luxurious Yee Low Mental Sanatorium, psychiatrist Xiao Tingqin (Tang Yifei) is assigned the case of "special" patient Sum Liu-sheung (Cherrie Ying), who claims to live both in the real world and 12 parallel universes, and appears to have special powers. As soon as they meet, Sum starts playing mind-games with Xiao, whose one-year-old marriage to independently wealthy policeman Zhen Shanlin (Stephen Fung) is already under serious strain, due to her workaholia and her aversion to being touched by him. Sum introduces Xiao to the scientific concept of "worm-holes", through which one can travel in time and to parallel universes, and stirs memories in Xiao of her past relationship both with Zhen and her first love, Ji Lü. Zhen's friendship with gourmet-food shop-owner Gu Xilin has also put further strain on her marriage, and one day, meeting them in the street, she starts to wonder whether Sum has enabled her to experience parallel versions of her life.

Nam is not your typical teenager. Sure, he spends a little too much time on his computer, and tries a little too hard to meet the gorgeous stewardess who lives in his building. But recently three of Nam's friends have committed suicide, which isn't all bad since, as the title implies, he sees ghosts. However, these suicides only foreshadow weirder things to come. Soon his brother Tung, along with Chee, his stewardess crush, begin to act strangely, while his visions of ghostly children and other phantoms grow more frequent. With aid from his brother's girlfriend Charlie, Nam sets out to investigate his haunted building's past and help these malevolent spirits cross over.