Former UN employee Gerry Lane, his wife Karin and their two daughters are in heavy Philadelphia traffic when the city is attacked by zombies. As chaos spreads, the Lanes escape to Newark, New Jersey and take refuge in an apartment, home to a couple with a young son, Tommy. UN Deputy Secretary-General Thierry Umutoni—an old friend of Gerry’s—sends a helicopter that extracts the Lanes and Tommy to a U.S. Navy vessel in the Atlantic where scientists and military personnel are analyzing the worldwide outbreaks. Dr. Andrew Fassbach posits that the plague is a virus, and that development of a vaccine depends on finding the origin. Gerry reluctantly agrees to help Fassbach find the outbreak’s source after it is made clear that he and his family will be removed from the ship if he does not.
Gerry and Fassbach fly to Camp Humphreys, a military base in South Korea, where they are attacked on arrival by zombies. Turning to re-enter the aircraft, Fassbach slips, falls and accidentally discharges his gun, killing himself. After being rescued by the base’s surviving personnel, led by Captain Speke, Gerry learns that the infection was introduced to the base by its doctor, who was ultimately incinerated by a soldier with a lame leg who the infected ignored. A former CIA operative, imprisoned at the base, tells Gerry to go to Jerusalem, where he says a safe zone has been maintained by the Israeli Mossad since before the outbreak’s official acknowledgement. As Gerry and his team bike back to their aircraft, zombies attack, kill several soldiers and infect Captain Speke, who commits suicide to prevent himself from turning. Gerry and his pilot escape.