In 1967 Hong Kong, three lifelong friends—Ben [Tony Leung], Paul [Waise Lee Chi-Hung], and Frank [Jacky Cheung]—live on the edge, belonging to a violent gang that constantly clashes with rival crews. When Ben becomes engaged to his girlfriend Jane [Fennie Yuen Kit-Ying], the pressure of impending marriage intensifies the danger surrounding them. Frank borrows money to pay for the reception, a reckless move that triggers a brutal confrontation with Ringo [Paco Yick Tin-Hung], the leader of another gang. The fight over the debt ends with Ringo dead, and the trio makes the fateful decision to flee Hong Kong to dodge the police. They hear rumors of easy money for smugglers in war-torn Vietnam and set their sights on a new, dangerous horizon.
The plan is simple in theory: move contraband from a Hong Kong smuggler to a Vietnamese contact, and ride out the chaos of war with profits in hand. They reach Saigon by boat, only to have their cargo wiped out by a Vietcong suicide bombing aimed at an ARVN officer. The trio is arrested and beaten, but the bomber is soon identified and executed. In the midst of the chaos, they meet Luke [Simon Yam], a ruthless hitman working for Leong, who dreams of leaving Vietnam behind with Sally [Yolinda Yan Chor-Sin], a nightclub singer forced into prostitution by Leong. A rescue mission to save Sally spirals into disaster, culminating in a fierce nightclub shootout. Amid the mayhem, Paul uncovers a box of gold hidden in Leong’s office and takes it for himself, while Sally is shot in the back and left gravely wounded.
With dawn comes a fragile hope as they wait by the river for a boat that will carry them out. Sally dies just as they manage to board, and Luke allows her body to drift away as the group pushes forward. The boat sustains damage and begins to sink, and Paul’s fixation on the gold drives a wedge between the old friends. Ben and Frank tell him that their friendship is finished, but the peril escalates when they are attacked by gangsters and ARVN forces. They manage to escape, yet Paul returns for the gold, almost drowning in the process, only to be saved by Ben and Frank, who ferry him back aboard with the loot.
Their ordeal does not end there. The three are captured by the Vietcong and dragged to a brutal camp where the gold is seized and intelligence documents are discovered inside the box Leong had planned to sell to the North Vietnamese. The captives endure brutal interrogations: Paul pretends to work for the CIA to save the others, and Frank is forced to kill fellow prisoners, a task that destroys him emotionally. Ben pleads to join in the resistance, but his attempt to fight back is rejected until a swift turn of events—an American squad led by Luke arrives—opens a path to escape.
The escape comes at a terrible price. Paul slips away with the gold into a field, while Frank, wounded, trails behind. He begs Paul for quiet, but his pain spills out, and Paul shoots him in the back to silence him. Luke arrives and ferries Frank away, still alive, onto a helicopter. Ben, meanwhile, pursues Paul back toward a river village where violence erupts anew. Paul massacres the villagers and attempts to flee with the gold, but Ben witnesses the carnage and survives a close encounter with death, aided by monks who rescue him.
Back in Saigon, Ben learns that Frank is still alive but forever altered—disfigured, addicted to heroin, and serving as a contract killer. Luke brings Ben to see him, and the reunion ends with a bitter, merciful decision: Ben shoots Frank to end his misery. The journey then turns homeward. Ben returns to Hong Kong and is reunited with Jane, who has since given birth to a child. In parallel, Paul builds a successful business career and lives with the weight of his choices. When Ben confronts him, he reveals Frank’s skull and accuses Paul of destroying their friendship; Paul remains cold and indifferent, even kicking Ben out.
A final, climactic confrontation unfolds on the streets and pier where their boyhood friendship began. A chaotic car chase erupts, and the two men crash onto the waterfront. Paul is killed, and Ben, scarred and exhausted, walks away into an uncertain future, carrying the heavy memory of a bond betrayed by greed, fear, and the brutal tides of war that shaped their fates.
