After buying a second-hand cab, Da Hua hopes to start afresh — but soon encounters a ghost in the vehicle and becomes a murder suspect.

To save the Hong Kong Police Force's Banshee Squad from becoming defunct, the struggling new squad members seek the help of former officers Amy (Sandra Ng), now a divorced mom with a young kid, and May (Kara Hui), now partially mentally-unstable, to help them with their training regiment, lead by Madame Yang (Cynthia Khan). Their police skills are put to the test when they are ordered to nab a band of brutal thugs in the city.