One Night in Bangkok follows the story of a seasoned hitman named Kai, who has just recorded his 500th kill. Tired of the life of killing, Kai decides to retire and return to his hometown in Japan. However, fate has other plans for him as he finds himself stuck in Bangkok due to a delayed flight.
While in Bangkok, Kai meets a young prostitute named Mei, who steals his wallet. In an effort to get his money back, Kai ends up getting caught up in an intricate web of deceit and power play involving the Thai mafia, corrupt politicians, and a ruthless businessman.
As Kai tries to navigate his way out of the situation, he realizes he has met his match in his arch-nemesis, a fellow assassin named Johnny. The two engage in a fierce battle of wits, each trying to outsmart the other and take control of the situation.
As the night unfolds, Kai must use all of his skills and experience to stay alive and protect Mei from the danger she unwittingly brought upon herself. In the end, Kai must make a choice that will determine the rest of his life.
