Lek, a Thai boxing coach, instructs a group of children in martial arts for their protection. He serves as both a mentor and a father figure to the kids—Wuth, Catt, Pong, and Jib. The group is also responsible for caring for Wuth’s younger brother, Woon, who suffers from a heart condition. Their lives take an unexpected turn when they encounter a gang of troublemakers, leading to Woon suffering a heart attack and requiring an urgent heart transplant. Unfortunately, the hospital where Woon is admitted is taken over by an international terrorist organization led by Paeda. The group finds themselves compelled to confront the terrorists, not only to save Woon’s life but also to defend their nation.