The film The Accidental Spy begins dramatically with a news crew covering a tragic event in an Anatolian village, where a mysterious pneumonia outbreak has claimed lives. A terrorist organization, masquerading as local farmers, launches a brutal attack amidst the chaos. As the screen fades from this violent encounter, we fast forward to a few days later, where a former North Korean spy makes an unexpected appearance at the Embassy of the Republic of Korea in Istanbul. This marks the official beginning of the story.
Two months further along in Hong Kong, we meet Buck Yuen, an exercise equipment salesman portrayed by Jackie Chan, who unintentionally disrupts a bank robbery and, as a result, gains unexpected fame. Later that evening, he crosses paths with a mysterious stranger named Manny Liu, who seeks men matching Yuen’s description for a dying Korean man named Park Won-jung, who wishes to bequeath his fortune to his long-lost son.
Yuen agrees to meet with Park and soon finds himself at a military hospital in South Korea. There, a reporter named Carmen approaches him with inquiries about Park. When Yuen returns to the hospital, he heroically saves Park from thugs and accepts an intriguing proposition: a game where victory means inheriting Park's wealth. Notably, Park gives Yuen a shiny crucifix, reminiscent of a significant item in his dreams from childhood. After Park's passing, Yuen discovers an engraved message on Park’s wife’s gravestone that reads, “wait for me.”
Intrigued, Yuen realizes this message corresponds to a phone number belonging to a bank in Istanbul. Once in Istanbul, he cleverly uses the crucifix to access Park's safety deposit box. Shortly after, he faces a robbery attempt for his briefcase, but he successfully holds off the attackers until law enforcement arrives. While sightseeing in Istanbul, Yuen encounters a captivating Chinese woman named Yong, who sports a scarf with the same embroidered message, further deepening the mystery.
During a visit to a Turkish bath, Buck is confronted by thugs demanding he hand over “the thing.” After a heart-pounding chase, he escapes but arrives late to his meeting with Yong. To his surprise, he learns that Carmen and her associate, Philip, are covert CIA agents. They reveal that "the thing" everyone seeks is a deadly biological weapon known as Anthrax II, responsible for previous deaths in Anatolia—a weapon Park developed which ultimately led to his brain cancer. Yuen learns that crime lord Zen is also on the hunt for this weapon and has sent Yong to glean intelligence from him.
After a tense encounter with Yong, who admits her loyalty lies with Zen, both Yuen and Yong are captured by thugs and dragged back to the village. Just when Yuen is being beaten into submission, mercenaries sweep in and eliminate the thugs, creating a chaotic escape route for Yuen and Yong. They end up confronting Zen, who manipulates the situation, promising Yuen money and Yong’s freedom in exchange for the Anthrax II. Although Yuen is hesitant, he realizes that the solution to their plight lies in a Bible located in the safety deposit box.
With the help of a priest familiar with Park, Yuen locates two vials of Anthrax II along with a note ominously declaring “game over.” Reluctantly, he hands over the vials to Zen, hoping to save Yong, only to discover he’s been double-crossed; she dies from a lethal dose of drugs at the station after he retrieves her. Distraught and imprisoned, Yuen is released by Carmen and Ashley, who inform him that the CIA plans to negotiate with Zen the following day.
Determined to put an end to the madness, Yuen takes action, attempting to thwart Zen’s escape at the airport. A sprawling car chase ensues, resulting in Yuen reclaiming the Anthrax II. However, the tension escalates as the car becomes wedged onto a fiery tanker heading for disaster. Yuen manages to save innocent lives but suffers severe injuries in the harrowing escape. When he regains consciousness in a hospital, Manny Liu reveals the shocking truth: Yuen’s wild adventure was orchestrated by the CIA, with him as an unwitting agent chosen for his unique background and skills.
In a gripping post-credits scene, now an official spy, Yuen is seen completing his mission by delivering a briefcase to a drug dealer in Italy, only to alert the police to make the arrest. This sets the stage for Yuen's new life in espionage, filled with action, intrigue, and unexpected challenges.
