Waking up in an empty hospital after weeks in a coma, County Sheriff Rick Grimes finds himself alone. The world he knows is gone, ravaged by a zombie epidemic. He goes searching for his wife and child, using his intelligence and training to stay alive. Eventually he reunites with his loved ones, who have gone on the run with a motley crew of survivors that include Rick's former partner on the force, who has fallen in love with Rick's wife.

A geophysical team, who are investigating the effect of radiation from other solar systems has on the Earth, learn that the core of the Earth is heating up and warn the President of the United States. While the leaders of the world race to build 'arks' to escape the impending doom, volcanic eruptions and earthquakes of unprecedented strength wreak havoc all over the world.