In the midst of a zombie outbreak, former UN investigator Gerry Lane, his wife Karin, and their two daughters take shelter in Newark while awaiting evacuation. The family sheltered with them choose not to accompany them and they are changed into zombies, with their son, Tommy, being the only one to escape. The Lane family takes him in.
The family is flown to a U.S. Navy carrier group while UN Deputy Secretary-General Thierry Umontoni oversees the worldwide governments' reactions. The scientists believe that they must find the origin of the outbreak, believed to be in South Korea. Gerry is coerced into joining a group of U.S. Navy Seals as they arrive in Camp Humphreys during a zombie attack. Gerry learns that the first person infected was a Korean doctor bitten by a soldier he was treating. a former CIA operative reveals that Israel had responded a week before the outbreak by building a giant wall around Jerusalem. Gerry is flown to Jerusalem and brought before Mossad agent Jurgen Warmbrunn, who reveals that he had intercepted a message from an Indian army fighting the zombies.
The zombies climb over the wall and overtake the city, forcing Gerry and the IDF agents to escape. In the midst of the chaos, Gerry notices the zombies avoid attacking the sick, injured and elderly. As Gerry and Segen, one of the agents, board a passenger jet, Gerry recounts the attack and how the zombies avoided the sick and elderly, leading him to believe this is evidence of a way to deal with them.
A zombie on the plane infects the other passengers, forcing Gerry to use a grenade to rupture the cabin, blowing the zombies out of the plane. The plane crashes and Gerry and Segen make their way to a World Health Organization facility, where Gerry falls into a coma. A few days later, Gerry regains consciousness days later and discovers that his family has evacuated to the mainlands, believing he had perished in the plane crash. Gerry explains to the WHO scientists that the zombies only attack the healthy and suggests injecting themselves with curable diseases to mask themselves from the zombies. As the zombies enter the facility, Segen and the scientists get to safety, but Gerry remains inside. He injects himself with one of the samples, and his theory is proven correct when the zombies ignore him. Gerry gets to safety and is cured of his disease.
Gerry and Segen are escorted to a refugee camp in Nova Scotia, where Gerry reunites with his family. Gerry explains that they have been using the diseases to create a masking agent, allowing them to rescue refugees from the zombies. Gerry then admits that it isn't over and that the war has only begun.