Rushing along the road every day with a vibrant mix of passengers of all kinds, what taxi drivers see and hear is far more varied than one can ever imagine. Retired taxi driver HO KAU (Kent Cheng) returns to the job after his son HO KA-PO (Raymond Wong) is convicted of causing death by dangerous driving. The incident has exacerbated the already fractious relationship between the father and the son. PO works for KAU after his release from prison. Before long, he has another serious road accident, in which KAU is also involved and severely injured, both mentally and physically. PO feels so guilty towards his father and comes to understand the importance of careful driving. He maintains a high degree of vigilance while driving but still gets picked on constantly by female traffic police officer KO LAI-SAM (Kate Tsui). As time goes by, the pair have gradually developed a strong attachment to each other and finally become lovers. But PO's ex-girlfriend CHEUNG HIU-MAN (Sonija Kwok) and SAM's grandmother KO LI SHUK-CHING (Lee Heung Kam) turn out to be the biggest obstacle to their relationship, leaving the pair stranded in dismay along the tunnel of love.
