Kuad and Kai are siblings who are apart from one another since their childhood. Kuad is brought up in a slum and supports his life by playing gambling whereas Kai is with his grandmother. When an accident causes grandmother to be in a coma and need more money for the cure, Kai begins searching for his brother Kuad. Things turn upside down when the siblings reunite to take their chance in a gambling house to get the money for grandmother.

时间回到2006年，泰国传出一条震惊世界的消息：天上掉下了某种奇异的物体。发现他们的当地人说这种东西是外星人，后来被证实只是用来消除寒热的胶状物质。《虫虫欲动》从一个欢乐的视角观察一个泰国小镇的生活是如何被天上掉下的外星人搅得天翻地覆的。