It won two TVB Anniversary Awards, including Best Actor for Louis Koo and Best Actress for Jessica Hsuan.

The series focuses on the lives of two detectives, Tsui Fei (Louis Koo) and Kong Chi Shan (Sunny Chan), and the murder cases they deal with.

While investigating his first murder case, Fei meets psychologist Quin Mo Chiu Kwan (Jessica Hsuan) and the two fell in love.

Sum Yu tries hard to stop loving Tze Shan, until Yuen Lan's father Man Kwok Tai (Law Lok Lam) kills Leung Kim Hung (Kwok Fung) - Tze Shan's fellow officer and Chin Chin's brother - in order to frame an old enemy.

Without Yuen Lan in the way, Sum Yu and Tze Shan quickly developed a relationship and even decided to marry.

Detective Investigation Files IV was shot with a whole new cast since the main stars of the original three installments, Michael Tao and Joey Leung, had left TVB.

Koo and Hsuan received the Favorite Actor and Actress Awards for the series in TVB's 32nd Anniversary respectively.

The scene takes place in a bar, where Mo Chiu Kwan is sitting watching soccer on TV.

TVB constantly receives requests to film the fifth in the series in which Tsui and Mo reunite, but so far there are no signs that it will happen.

Although Sunny Chan returned to TVB in 2004 (and even starred in a drama with Jessica Hsuan), the Detective Investigation Files phenomenon had already faded by that time.