The scene changes to Andrew, a young American photojournalist, who is hired by his wealthy employer to get the latter's daughter Samantha back to the United States from San José, Central America. Andrew has no interest in being an escort, while Samantha seems at odds with her impending marriage to her fiancé.
While traveling to the Mexican coast to get a boat to the United States, the pair are temporarily slowed down by the destruction of the railroad. If they do not leave the country within a few days, sea and air travel will be blocked, and they will have to wait six months before safe travel is possible.
Arriving at the port, Andrew buys Samantha a ferry ticket to return to America the next morning at 7 o'clock. That night, they drink together, but it soon becomes obvious Samantha wants to go to bed alone.
The next morning, Samantha is unable to get on the ferry, since Andrew was robbed of their passports by the local girl with whom he spent the night. Samantha barters her engagement ring for an escort through the infected zone.
Their journey takes them across Mexico by boat and by convoy with armed guards. As they are travelling their car is attacked by the aliens. The guards are all killed, leaving Andrew and Samantha to travel alone. Eventually, they arrive at the large border wall separating the Infected Zone from the United States. As they cross the checkpoint, Andrew and Samantha realize the American border has been evacuated, and the aliens have advanced into the United States.
After walking along an evacuation route, the two stumble across an abandoned gas station. Andrew calls the police and is informed they will be picked up.
Andrew and Samantha phone their families. As they finish their calls, an alien appears at the gas station, but it turns out there are in fact two aliens who are communicating with each other - rather than being monstrous, the giant creatures display tenderness, even beauty.
As they watch them leave, Samantha declares, "I don't want to go home." Andrew and Samantha share a brief kiss, interrupted when the army arrives to pick them up.
As the military convoy arrives, it is revealed that the opening scene shows what happens after Andrew and Samantha are picked up, since the viewer hears the soldier humming Wagner's "Ride of the Valkyries". [Plot summary provided by WikiPedia]