Volcanoes, earthquakes, and tornadoes all can cause enormous damage, and predicting where and when they will strike is of great importance. Volcanologist Dr. Marie Edmonds has devised sensors that monitor the underground activity of magma to better predict future eruptions on the Caribbean island of Monserrat, the site of the massive 1995 eruption captured for this film. Geophysicist Dr. Ross Stein studied the earthquake repair records in Istanbul's Hagia Sophia over the centuries to find clues about the history of earthquakes in Turkey. He discovers a pattern in quakes along the long North Anatolian Fault system, including the massively destructive quake at Izmit in 1999, and predicts the next earthquake just a few miles south of Istanbul. Dr. Joshua Wurman and his team chase tornados in trucks equipped with Doppler radar in an attempt to probe the interior of a tornado just as it is born.
39歲的布倫南?哈夫（威爾?法瑞爾 Will Ferrell 飾）無業(yè)，一直在母親南希（瑪麗?汀伯根 Mary Steenburgen 飾）家蹭吃蹭住。40歲的戴爾?多巴克（約翰?賴利 John Reilly 飾）也是個與父親羅伯特（理德?詹金斯 Richard Jenkins 飾）住在一起的大齡男，靠父的接濟生活。南希與羅伯一見鐘情，婚后搬入羅伯家居住，布倫南也隨母親起搬入，從此被迫以繼兄的身份與戴爾同處一室。人從相互敵視逐漸成為最拍檔，共同對付布倫南的秀弟弟德里克（亞當?斯特 Adam Scott 飾），玩鬧得不亦樂乎。可沒想到他們的胡作非為毀了父母剛建立起來的美婚姻，二人后悔萬分，終決定痛改前非…?
