When Hui returned to Hong Kong after her stay in London, she became the assistant to the prominent Chinese film director, King Hu. Her breakthrough directorial work began with several drama series and short documentaries on 16mm for the Television Broadcasts Limited (TVB) television station. During 1977, Hui produced and directed half a dozen films for the Independent Commission Against Corruption (ICAC), a Hong Kong organization created to clean up government misconduct. Two of these films were so controversial that they had to be banned from airing. A year later, Hui directed three episodes of Below the Lion Rock, a documentary series depicting the lives of people from Hong Kong, under the public broadcasting station, Radio Television Hong Kong (RTHK). The most recognized episode of Hui's is "Boy from Vietnam" (1978), which is the start of her "Vietnam trilogy."