Four Middle Eastern terrorists led by Ahmed Musa Mohammed infect themselves with the smallpox virus from a dying child they find with the natural disease in rural Somalia and travel to the United States to deliberately spread the infection among the crowds of Christmas shoppers in four American cities. Dr. Harry Bennett, a physician practicing near Chicago, sees the first two cases of smallpox, a mother and daughter, and he watches helplessly as they become seriously ill and die. A few days later, Dr. Vicky Anderson, an emergency room physician in New York City, diagnoses the third case. The...

Sam Harper, a rural Oklahoma preacher and leader of a fanatic militia group, conspires to hold the attorney general of the United States, Ronald Montgomery, hostage with a radio-controlled nitrate-and-fuel-oil bomb. Montgomery, who is Harper's avowed enemy, is speaking at a Tulsa hotel, and just before Harper reveals his plan, Montgomery suffers a massive heart attack and is rushed to a nearby hospital intensive care unit. Harper decides to plant the bomb in the stairwell close to Montgomery's room, but when a security guard interrupts Harper and his militia members, Harper seizes the...