When the branch leader position is open for Tuen Mun, Chicken decides to run for it and is up against fellow Hung Hing member "Barbarian", who resorts to ruthless Tung Sing member "Thunder Tiger" (Roy Cheung) for help in his candidacy. The triad also has to deal with finding a new chairman to the Hung Hing Society, Chiang Tin Yeung (Alex Man), Chiang Tin Sang's older brother, who resides in Thailand. Young and Dangerous 4 also brings in new characters first appearing among the Hung Hing ranks, such as Ben Hon (Wan Yeung Ming), "Sister 13" (Sandra Ng) and "Prince".
Two not-too-bright party girls reinvent themselves for their high school reunion. Armed with a borrowed Jaguar, new clothes and the story of their success as the inventors of Post-it notes, Romy and Michele descend on their alma mater, but their façade crumbles quickly.
Professor Phillip Brainard, an absent minded professor, works with his assistant Weebo, trying to create a substance that's a new source of energy and that will save Medfield College where his sweetheart Sara is the president.
Three detectives in the corrupt and brutal L.A. police force of the 1950s use differing methods to uncover a conspiracy behind the shotgun slayings of the patrons at an all-night diner in this lush tribute to tough film noir crime films.