A couple on a holiday in the Caribbean decide to spend the day on a scuba diving trip. But was it the wrong decision? When a mis-count happens on the boat, Susan and Daniel are left behind in the middle of the ocean, the boat long gone. With all their hopes set on the boat coming back to rescue them, they try to keep themselves safe, especially when sharks start to appear.

In a near-empty Northfork orphanage, Father Harlan gently tends to Irwin, an eight-year-old who lies between a dream state and death. As orphanage caretaker Harlan reads aloud about Northfork's years-ago forced evacuation to make way for a hydro-electric dam, Irwin's imagination takes flight. While a team of six men evacuate the last remaining citizens of the town, Irwin, too, invents a cast of characters to prepare himself for his own evacuation. (the above states the caretaker - who is actually the priest - is reading about a years-ago evacuation. In the movie, the evacuation is taking place as the boy lays dying!)

Months after the events of the original film, Ming suspects a police superintendent as being a new mole for the triads, while years earlier, Yan embarks on his first mission.

In this prequel to Mou gaan dou (2002), Chan Wing Yan has just become an undercover cop in the triads while Lau Kin Ming joins the police force. Both the triads and the police find an enemy in a rival crime boss.