Deputy Sheriff Rick Grimes and his partner, Shane, are in a shoot-out with an escaped prisoner on a highway. Rick is shot in the shoulder during the incident and falls into a coma. A month later, Rick wakes up in a hospital, but finds it abandoned.
After dressing himself, he explores the hospital, finding a corpse which falls backward into the opening elevator, as well as a cafeteria door blocked by a piece of wood. Rick removes the wood and opens the door only to find multiple zombies inside the room. One of the zombies lunges at Rick, which causes both of them to fall down a set of stairs where the zombie's head falls off.
Rick ties his belt onto the handles of the door behind him to hold back the other zombies. Severely confused, Rick leaves the hospital and finds a bicycle. As Rick walks toward the bicycle he sees a zombie that has deteriorated to nothing more than bones. At this sight, Rick temporarily breaks down.
Shortly after, Rick uses the bike to return to his home and finds that his house has been looted and that his wife and son(Lori and Carl) are both gone. Upon exiting his home, Rick is knocked unconscious by a boy (Duane Jones) with a shovel. The boy's father (Morgan Jones) quickly tells him that Rick is not a zombie, and they bring him inside.
Rick wakes up and has dinner with Morgan and Duane. Morgan explains to Rick the nature of the outbreak, explaining it had started just over a month ago. Rick finds out that, before the media shut down, the government told everyone to relocate to major cities in an effort to protect them.
Morgan then states that he thought he would be safer away from large cities. Rick decides that Lori would have taken Carl to Atlanta where her parents live. Rick, Morgan, and Duane go to the Cynthiana Police Department in order to get supplies. Rick gives Morgan and Duane some guns and a police car while changing into a police uniform, while filling a bag with guns to take with him.
Morgan and Duane decide to stay behind while Rick plans to go search for his family in Atlanta. Morgan thanks Rick for his generosity, while Rick advises Morgan to make sure he uses his police equipment sparingly in order to return it in good condition when the outbreak is dealt with. However, their goodbye is interrupted when a zombie reaches for them from behind the parking lot fence.
Rick nearly shoots it, but is stopped by Morgan, who advises him not to waste the bullet. Rick and the Jones' part ways. On his way out of Cynthiana, Rick returns to find the severely decomposed bike zombie and puts it out of its misery, and then sheds a tear.
On his way to Atlanta, Rick's car runs out of gas forcing him to scavenge for gasoline at a nearby ranch. Inside the home, Rick finds the remains of a family that committed a religiously motivated group suicide.
After throwing up from their smell, Rick continues to explore the property when he finds a horse and hatchet inside the family's barn. Rick takes the hatchet and horse out of the barn, planning to use the hatchet as a weapon and the horse to get to Atlanta in place of his incapacitated vehicle.
Rick talks to the horse, reminiscing about how things were before the outbreak. He recounts to the horse the events of the day his son, Carl, was born, stating it was the happiest day of his life.
As he continues into the emotional climax of laying eyes on his son for the first time, Rick realizes that thinking about the good old times makes the outbreak seem much worse, opting for silence for the remainder of his trip.
Rick arrives in Atlanta and enters the city, only to find it in ruins. As he progresses into the city, zombies begin to congregate and swarm him, knocking him off of his horse. As he sees his horse being eaten by zombies, he begins shooting and bashing oncoming zombies, shouting out "What's the matter with you!?"
