Mt. Paektu, an active volcano straddling the China-North Korea border, suddenly erupts, causing severe earthquakes in both North and South Korea. Pandemonium ensues on the Korean peninsula, with more eruptions predicted in the area.

To prevent another disaster, Jeon Yoo-kyung (Jeon Hye-jin) plans an operation based on a theory by Professor Kang Bong-rae (Ma Dong-seok), who had studied Mt. Baekdu and its possible future eruptions.

Jo In-chang (Ha Jung-woo) is assigned to be the captain of a special forces team taking part in the operation. Jo In-chang contacts Lee Joon-pyeong (Lee Byung-hun) who is part of the Korean People's Army in North Korea as a spy. Meanwhile, Jo In-Chang's pregnant wife Choi Ji-young (Bae Suzy) is alone in Seoul and struggling to survive amidst the disaster.