Plainclothes policemen Brian and Mike use an elderly woman's apartment for surveillance, hoping to catch a fugitive gangster. They develop a warm relationship with their hostess, whom they call "granny." Meanwhile, each man develops a romantic relationship: Brian with a strange wandering teenage girl, and Mike with a pregnant woman at the dry cleaning shop. When the gangster returns to his flat, Brian and Mike are forced into an explosive confrontation.

Louis Koo plays an assassin who wants to go straight after getting out of prison, so he turns down a job from his former employer Simon Yam to kill a politician. Yam carries out the hit himself and manages to frame Koo for the crime, who then must run from both the cops and criminals as he tries to clear his name.

The "walk in" of the title refers to one person allowing another's soul to take possession of his body at the time of death.

Former member of a triad, Sun seeks to emigrate to Canada. He decides to become a great chef of chinese cooking and follows the teaching master Au.