The Day After

The story follows several citizens and people they encounter after a nuclear attack on Lawrence, Kansas and Kansas City, Missouri. The film's narrative is structured as a before-during-after scenario: the first segment introduces the various characters and their stories, the second shows the nuclear disaster itself, and the third details the effects of the fallout on the characters.
Dr. Russell Oakes (Jason Robards) lives in the upper-class Brookside neighborhood with his wife (Georgann Johnson) and works in a hospital in downtown Kansas City. He is scheduled to teach a hematology class at the University of Kansas (KU) hospital in nearby Lawrence, Kansas, and is en route when he hears an alarming Emergency Broadcast System alert on his car radio. He exits the crowded freeway and attempts to contact his wife but gives up due to the long line at a phone booth. Oakes attempts to return to his home via the K-10 freeway and is the only eastbound motorist. The nuclear attack begins, and Kansas City is gripped with panic as air raid sirens wail. Oakes' car is permanently disabled by the electromagnetic pulse from the first high altitude detonation, as are all motor vehicles and electricity. Oakes is about 30 miles (48Â km) away from downtown when the missiles hit. His family, many colleagues, and almost all of Kansas City's population are killed. He walks 10 miles (16Â km) to Lawrence, which has been severely damaged from the blasts, and, at the university hospital, treats the wounded with Dr. Sam Hachiya (Calvin Jung) and Nurse Nancy Bauer (JoBeth Williams). Also at the university, science Professor Joe Huxley (John Lithgow) and students use a Geiger counter to monitor the level of nuclear fallout outside. They build a makeshift radio to maintain contact with Dr. Oakes at the hospital as well as to locate any other broadcasting survivors outside the city.
Billy McCoy (William Allen Young) is an Airman First Class in the United States Air Force, stationed at Whiteman AFB near Kansas City, and is called to duty during the DEFCON 2 alert. As a missile repair technician at a Minuteman silo, he is among the first to witness the initial missile launches, indicating full-scale nuclear war. After it becomes clear that a Soviet counterstrike is imminent, the airmen panic. Several airmen stubbornly insist that they should stay at their post on duty and take shelter in the silo, while others, including McCoy, point out that it is futile because the silo will not withstand a direct hit. McCoy tells them they have done their jobs and speeds away in an Air Force truck to retrieve his wife and child in Sedalia, but the truck is permanently disabled and stalls from the EMP effect of the first high altitude detonation. Realizing what has happened, McCoy abandons the truck and takes shelter inside an overturned semi truck trailer, barely escaping the oncoming nuclear blast. After the attack, McCoy walks towards a town and finds an abandoned store, where he takes candy bars and other provisions, while gunfire is heard in the distance. While standing in line for a drink of water from a well pump, McCoy befriends a man who is mute and shares his provisions. McCoy asks another man, who is walking along the road with other injured survivors, what happened to Sedalia, and the man indicates that Sedalia and Windsor no longer exist. As McCoy and his companion both begin to suffer the effects of radiation sickness, they leave a refugee camp and head to the hospital at Lawrence, where McCoy ultimately succumbs to the radiation sickness.
Farmer Jim Dahlberg (John Cullum) and his family live in rural Harrisonville, Missouri, about 37 miles (60Â km) from Kansas City[4] but very close to a field of missile silos. While the family is preparing for the wedding of their elder daughter, Denise, to KU senior Bruce Gallatin, Jim is forced to prepare for the impending attack by converting their basement into a makeshift fallout shelter. As the missiles are launched, he forcefully carries his wife Eve (Bibi Besch), who refuses to accept the reality of the escalating crisis and continues making wedding preparations, downstairs into the basement. While running to the shelter, the Dahlberg's son, Danny, inadvertently looks directly at a nuclear explosion and is flash-blinded.
A KU student, Stephen Klein (Steve Guttenberg), while hitchhiking home to Joplin, Missouri, stumbles upon the farm and persuades the Dahlbergs to take him in. After several days in the basement, Denise, distraught over the situation and the unknown whereabouts of Bruce, who, unbeknownst to her, was killed in the attack, escapes from the basement and runs about the field that is cluttered with dead animals. She sees a clear blue sky and thinks the worst is over. However, the field is actually covered in radioactive fallout. Klein goes after her, attempting to warn her about the effects of the nuclear radiation that â though invisible, intangible, and tasteless â is going through her cells like x-rays, but Denise, ignoring this warning, tries to run from him. Eventually, Klein is able to chase Denise back to safety in the basement, but not before Denise runs to the stairs to find her wedding dress. Because she ran about the contaminated field, Denise slowly develops radiation sickness and, during a makeshift church service, she begins to bleed externally, while the minister tries to express how lucky they are to have survived and a Presidential address remarks that there is a ceasefire between the United States and the Soviet Union, which has suffered similar damage, and states that there has not been and will not ever be any surrender by the United States.
Klein takes Danny and Denise to Lawrence for treatment. Dr. Hachiya unsuccessfully attempts to treat Danny, and Klein also develops radiation sickness. Dahlberg, upon returning from an emergency farmers' meeting, confronts a group of survivors squatting on his farm and is shot and killed.
Ultimately, the situation at the hospital becomes grim. Dr. Oakes collapses from exhaustion and, upon awakening several days later, learns that Nurse Bauer has died from meningitis. Oakes, suffering from terminal radiation sickness, decides to return to Kansas City to see his home for the last time, while Dr. Hachiya stays behind. Oakes hitches a ride on an Army National Guard truck, where he witnesses military personnel blindfolding and executing looters. After somehow managing to locate where his home was, he finds the charred remains of his wife's wristwatch and a family huddled in the ruins. Oakes angrily orders them to leave his home. The family silently offers Oakes food, causing him to collapse in despair, as a member of the family comforts him.
As the scene fades to black, Professor Huxley calls into his makeshift radio: "Hello? Is anybody there? Anybody at all?" There is no response.

Question: How does McCoy die?
Answer: radiation sickness