The Viral Factor is a 2012 Hong Kong-Chinese action film directed by Dante Lam and starring Jay Chou and Nicholas Tse. The supporting cast includes Lin Peng, Michelle Bai, Andy On, Carl Ng, Liu Kai-chi and Elaine Jin, with action direction by Chin Kar-lok. Production for the film started in March 2011, and was theatrically released on January 17, 2012.
Plot
IDC (International Defense Commission) agent Sean Wong (Andy On) and his team members are in Jordan on a dangerous mission to escort a scientist named Kenner Osama Muhammad, who has stolen a copy of the smallpox virus, to Norway. On the way out of the country, the convoy were ambushed by a group of assailants. It was later revealed that Sean has betrayed the team for his own agenda and shot his colleagues Jon Man (Jay Chou) and his girlfriend Ice (Michelle Bai). Sean then escapes with Kenner and the virus. The failed mission left Ice dead while Jon has a bullet lodged in his brain with no safe way to remove it and only two weeks to get his affairs in order before succumbing to permanent paralysis. Three months later, the crew of a freight ship on Malaysian waters was found to have been infected and killed by the smallpox virus. However this plan backfires when Kenner escapes only to killed accidentally by getting ran over by a random passerby truck, forcing Sean to make plans to intercept a replacement specialist. Elsewhere, Sean contacts an arms dealer called Tyler (Jared Robinson), and suggests to mutate the virus into a biological weapon, develop a vaccine and sell it to a corrupt pharmaceutical company. In Beijing, Jon returns home to spend his remaining days with his mother (Elaine Jin), who tells him that he has a long lost brother, Man Yeung (Nicholas Tse) whom she left behind with his father, Man Tin (Liu Kai Chi).
In Kuala Lumpur at a Malaysian court, Man Yeung is being charged for numerous crimes that he had committed. While being escorted to the prison, he attacks the police personnel and makes a successful escape. He later meets up with corrupt police officer Russell (Philip Keung), who aided in his escape from custody and was given a new job. On his flight to Malaysia, Jon meets Asian Centre for Disease Control and Prevention (ACDC) doctor Rachel Kan (Lin Peng), who was later abducted by Yeung after the plane landed. A suspicious Jon, who noticed that the car that Rachel was travelling in has a different driver from earlier, tails the vehicle and ended up being forced into the vehicle. Jon, unaware of Yeung's identity, puts up a fight against him and the other henchmen, causing the car to crash. Yeung escapes after a brief struggle with Jon. Later, Jon meets his father and Man's daughter, Cheung-sing, who shows him a newspaper article that the man he encountered earlier was his brother.
Meanwhile, Yeung and his goons breaks into Rachel's house, who holds her mother hostage and forces her to get a Carnot virus sample from the ACDC headquarters. The next day, while Yeung and Rachel are leaving the building after obtaining the virus sample, a security personnel triggers the alarm, causing a chase through the city. During the chaos several ACDC guards and Yeung's partners are killed and Rachel is re-captured by Mark (Sammy Hung), Sean's right hand man working with Russell. Yeung crashes the getaway vehicle and flees on foot but is pursued by Russell and his corrupt cops who want him silenced. He calls his father and tells him to bring Cheung-aing to meet him at the train station. Jon, who was nearby to meet up with Rachel, witnesses the event and join in the pursuit of Yeung. Working together, Jon and Yeung manages to hold off the corrupted police officers long enough for them to board a train to escape. Jon persuades Yeung to surrender himself but the two brothers got embroiled in a fist fight. They were later intercepted by the Russell and police at a train depot, where Tin sacrifices himself in order to let Yeung and Cheung-aing escape, but Cheung-aing was caught by a corrupt cop and Jon arrested by the police.
Russell then discovers that Jon and Yeung are brothers, and orders his men to kill Jon, who is at a hospital for a check-up. Yeung later follows Russell to a nightclub, who was meeting Sean. After being assaulted by Yeung to release his daughter, Russell escapes and runs to the road only to be knocked down by a bus, killing him instantly. At the hospital, Russell's men failed to kill Jon, who escapes after putting up a fight.