Pint-sized Wun and his older brother live at a Muay Thai school with a few other students. Suffering from a failing heart, Wun is hospitalized and in desperate need of a transplant. A viable heart becomes available, but the donated organ is locked up in a hospital that has been overtaken by a lethal terrorist faction. With only four hours to perform the surgery, Wun's brother and best friends, armed with Thai boxing skills and determination, race to the hospital to take on the terrorists and save his life.