Ray Nettles, a detective of San Francisco, and his partner Fuzzy must take up to one of the most dangerous terrorist gangs of the city. When one of the terrorists, the beautiful scientist Claire Manning is arrested, Swan, the leader of the terrorists, claims he will detonate bombs throughout the city if she is not released. Because of the possible bloodshed, Nettles calls for the help of explosive expert Frank Glass...

Park Jung-gu sends out homemade bombs to people he finds online who are likely to use them, yet these devices are unused. One day, Jung-gu meets Lee Hyo-min, a delinquent student at his university and sends him a package. Soon an explosion in a delivery truck hits the news. Before long, Hyo-min discovers who is sending him the packages and the two form a tenuous relationship. However, Hyo-min's unpredictable behavior becomes dangerous and Jung-gu finds himself caught in a situation that he can no longer handle.