Harper—a college student looking for adventure in Europe—is exploring the picturesque landscape of Slovakia with her friends when things take a deadly turn. Within a blink of an eye, a carefree vacation turns to death and destruction. People around them are dying without explanation. Death is fast, and painful, and apparently highly contagious. Ninety-five percent of people in the death zone fall prey to the killer within minutes. To survive, Harper and her friends must get out of the death zone to the quarantine center at the Czech border.