After many years apart, Detectives Lee and Carter are living very different lives: Lee is now a high‑ranking official in the Hong Kong Police Force, mentoring younger officers, while Carter has taken on an advisory role in Los Angeles, doing less detective work and more public speaking. When a prominent U.S. Senator is mysteriously assassinated in Las Vegas using a rare Chinese poison dart, the case has diplomatic repercussions and dangerous international undercurrents. The Las Vegas Police Department calls in Deputy Chief Palma, who immediately asks both Carter and Lee to join the investigation, given Lee’s Hong Kong expertise and Carter’s track record with high‑stakes cross‑border cases.
Reluctantly reunited, Lee and Carter travel to Las Vegas, where the crime scene hints at involvement from a powerful underground group trafficking in forbidden bioweapons and toxins. Carter, with his loud personality and bluster, clashes again with Lee’s disciplined martial arts calm, but their old chemistry — with its mix of comedy and tension — quickly returns. Alongside the official investigation, Lee suspects there is a political plot to frame Chinese nationals and stir unrest, while Carter uncovers clues that tie the poisoning to an old nemesis they thought defeated years ago.
As the pair dive deeper, they follow leads that take them from the glitter of the Las Vegas Strip to hidden labs in the Nevada desert, then on to shadowy offices in Hong Kong. They are joined by a local forensic scientist and an ambitious journalist, both of whom help them piece together the clues: a rare poison, smuggled through clandestine trade routes, and a conspiracy involving bribed politicians on both sides of the Pacific. Carter’s bravado keeps their morale up; Lee’s precision and experience keep them alive during a series of ambushes, car chases, and a knife fight atop a moving vehicle.
Tensions mount when they realize that someone very close to Carter is implicated as an unwilling pawn in the plot. Lee must decide whether to follow bureaucratic protocols or act on instinct when official channels are blocked. Meanwhile, Carter’s old flashy style proves dangerous at times, putting them in situations they narrowly escape. The villains behind the poisoning plan to provoke a diplomatic crisis, hoping to destabilize relations between the U.S. and China.
In a climactic showdown in Hong Kong, Lee and Carter expose the mastermind behind the conspiracy during a public event attended by dignitaries. With a mix of martial arts, clever disguise, and witty banter, they prevent a mass poisoning and deliver justice. Carter and Lee reaffirm their partnership, visible as older, wiser versions of themselves, still capable of great action and humor. The film ends with them teasing one another about retirement — but clearly both too in love with the chase to give it up just yet.
