The novel begins with the man and boy in the woods, the boy asleep, as the two of them are making their journey along the road. The story is set in a post-apocalyptic world, date and place unnamed, though the reader can assume it's somewhere in what was the United States because the man tells the boy that they're walking the "state roads." Neither the man nor the boy is given a name; this anonymity adds to the novel's tone that this could be happening anywhere, to anyone. Stylistically, the writing is very fragmented and sparse from the beginning, which reflects the barren and bleak landscape through which the man and boy are traveling. McCarthy also chooses to use no quotation marks in dialogue and for some contractions, he leaves out the apostrophes. Because this is a post-apocalyptic story, the exemption of these punctuation elements might serve as a way for McCarthy to indicate that in this new world, remnants of the old world — like electricity, running water, and humanity — no longer exist, or they exist in very limited amounts.
While the boy sleeps, the man reflects upon one of his dreams of a creature with dead eyes. The man's dreams play a large role throughout the novel; the man tells both himself and the boy that good dreams are to be feared because they indicate a form of acceptance, and that death would inevitably be near. Bad dreams, on the other hand, are reassuring because they demonstrate that the man and boy are still persevering in the world they inhabit.
From the start, it's clear that the boy is all the man worries about. He is all the man has, and the man believes that he's been entrusted by God to protect the boy. He keeps a pistol with him at all times, unless he goes inside a house. Then he gives the pistol to the boy. The pistol, though, only has two bullets.
The man, too, is all the boy has. When the boy wakes, they set out on the road yet again, making their way through a "nuclear winter" that follows them from start to finish as they make their way south to the coast, hoping to find a better life there, although the man knows there's no reason for him to hope that things will be different for them there. They have a grocery cart with them, filled with their belongings and supplies for their journey. They are running low on food, and the man is fighting a bad cough, one that sprays blood on the gray snow.
They come upon towns and cities that are mere shells of what they once were. Remnants of the old world often — like houses, billboards, and hotels — clash with the reality of the new world, reminding the man of the life he once lived. The man remembers an evening spent on the lake with his uncle. And he remembers his wife — who left him and the boy, presumably to kill herself and escape this horrible new world.
In one grocery store, the man finds a pop machine that has a single Coca-Cola in it. He retrieves it for the boy and lets him drink it. The man likes to offer whatever he can to his son to make his world a bit more pleasant and to give him glimpses into the world that existed before him.
The man and boy come upon the house where the man grew up. The boy is scared of this house, as he is of many of the houses. The boy worries they'll run into someone, like the roadagents or bad guys who eat people in order to survive. The man has decided, too, that should roadagents find them, that he will kill the boy so that they cannot torture him, but he often wonders to himself if he would be able to do it if the time should ever come.
They come upon a waterfall and the man and boy swim together, the man teaching the boy how to float. It's a tender moment that suggests lessons that fathers would have taught their sons in the old world. Throughout the novel there are moments like this one at the waterfall, scenes that prove the bond between fathers and sons still exist in this new world. It exists, in many ways, just as it did before. The father cares for his son, and teaches his son, and worries about his son's future under such uncertain circumstances.
The boy is very concerned with making sure they are "carrying the fire," assuring himself that he and his father are the good guys as opposed to the bad guys (who eat dogs and other people). The man tells the boy stories of justice and courage from the old world in the hopes that such stories will keep the fire alive in the boy. The man hopes for a future that might again also harbor courage, justice, and humanity.
As they walk, they keep track of their location on a worn and tattered map that they must piece together like a puzzle each time they use it. While on the road, they come upon a man who's been struck by lightning. They pass the burnt man and the boy wants to help him, but his father says they've got nothing to give him. The boy cries for the man, showing his kind heart and his compassionate nature in a world where very little humanity exists.
The man has flashbacks about leaving his billfold behind earlier in the journey, after his wife left him and the boy. He recalls that he also left behind his only picture of his wife, and ponders whether he could have convinced her to stay alive with them. The man remembers the night that his son was born, after the clocks all stopped, how he'd delivered the baby himself, marking the beginning of their intense father/son bond.
A truck full of roadagents comes upon the man and the boy, who hide in the woods. The truck breaks down and one of the bad men finds them in the woods. The bad man grabs the boy, and the boy's father shoots the man in the head and both escape into the woods. Now the pistol has only one bullet left, and the man knows that this bullet is for his son should the time come. The boy wants to know if they are still the good guys, despite his father's committing a murder. His father assures him that they are.
The man views his son as a holy object, something sacred. The boy is a source of light for the man and the man believes that if there is any proof of God, the boy is it.
The man and boy are cold and starving, as they are for most of the novel. As they travel, they are on a constant lookout for food, clothing, shoes, supplies, and roadagents. In one town, the boy thinks he sees a dog and a little boy and tries to chase after them. He worries about the other little boy for the rest of the novel.
By the time they come upon a once grand house, the boy and man are starving. There are suspicious items in the house, such as piles of blankets and clothes and shoes and a bell attached to a string, but the man these. He finds a door in the floor of a pantry, and breaks the lock. The boy becomes frightened and repeatedly asks if they can leave. In the basement, the man and boy find naked people who are being kept alive for others to eat. The man and boy flee just as the roadagents return. They hide in the woods through the freezing night, the man feeling certain that this is the day when he's going to have to kill his son. But they survive the night and go undiscovered.
They continue their journey, exhausted and still starving. The man leaves the boy to sleep while he explores, and he finds an old apple orchard with some dried out apples. He continues to the house that's adjacent to the orchard, where he finds a tank of water. The man fills some jars with water, gathers the dried apples, and takes them back to the boy. The man also found a dried drink mix, grape flavored, which he gives the boy. The boy enjoys the drink and their spirits are lifted for a moment.
The man and boy move on, but the perceptive boy asks his father about the people they found in the basement. The boy knows that the people are going to be eaten and understands that he and his father couldn't help them because then they may have been eaten, too. The boy asks if they would ever eat anyone, and his father assures him that they wouldn't. They are the good guys.
They press on, enduring more cold, rain, and hunger. Nearing death, the man's dreams turned to happy thoughts of his wife. They come upon another house, and the man feels something strange under his feet as he walks from the house to the shed. He digs and finds a plywood door in the ground. The boy is terrified and begs his father not to open it. After some time, the man tells the boy that the good guys keep trying, so they have to open the door and find out what's down there. What they discover is a bunker, full of supplies and canned food, cots to sleep on, water, and a chemical toilet. It is a brief sanctuary from the world above. The man realizes that he'd been ready to die, but they would live. This is hard for the man to accept. The man and boy stay in the bunker for days, eating and sleeping. The boy wishes he could thank the people who left these things. He's sorry that they're dead, but hopes they're safe in heaven.
The man whittles fake bullets from a tree branch and puts them in the pistol with the one true bullet. He wants the gun to appear loaded should they encounter others on the road. They go into town to find a new cart and return to their bunker to load up with supplies. In the house, the man shaves and cuts both his own hair and the boy's — another moment in the novel that recalls a father/son ritual of the old world. They plan to leave the next day, but the following morning they wake up and see rain, so they eat and sleep some more to restore their strength. Then, they set out on the road again, still heading south.
They come upon another traveler on the road, an old man who tells them his name is Ely, which is not true. Ely is surprised by seeing the boy, having convinced himself that he never thought he'd see a child again. The boy persuades his father to let Ely eat dinner with them that night. The man agrees, but tells his son that Ely can't stay with them for long. Later that night, the man and Ely talk about the old world, about death, God, and the future — particularly, about what it would be like to be the last human on the planet. The next day as they prepare to part ways, the boy gives Ely some food to take with him. His father reluctantly gives away their supplies. As Ely moved on, the boy is upset because he knows that Ely is going to die.
As they continue moving south, the man and boy run into other towns and landscapes that act as skeletons of the old world, both literally and metaphorically. They see bones of creatures and humans alike, as well as empty houses, barns, and vehicles. They find a train in the woods, and the man shows the boy how to play conductor.
The boy asks his father about the sea. He wants to know if it's blue. The man says it used to be. The man has a fever, which causes the two to camp in the woods for over four days. The boy is afraid his father is going to die, and the man's dreams turn to dead relatives and better times in his life. The boy's dreams continue to be bad, and the man encourages him, saying that his bad dreams mean he hasn't given up. The man says he won't let his son give up.
When they set out again, the man is even weaker than before. They come upon numerous burned bodies and melted roads that have reset in warped shapes. There are people following them: three men and a pregnant woman. The man and boy hide and let the group pass. Later, the man and boy come upon their camp and discover the baby skewered over a fire. The boy doesn't speak for over a day. Then, he asks about the baby; he doesn't understand where it came from.
Their arrival at the coast is anti-climactic. The water looks gray and the boy is disappointed. It looks as if, even at the southern coast, life isn't sustainable. But the boy, with his father's encouragement, runs to the waves and swims in the ocean, which lifts both his and his father's spirits.
From the shore, the man and boy see a boat in the water. The man swam to the boat and explores it, finding supplies, including some food, a first-aid kit, and a flare gun. He and the boy make their camp close to the beach, plundering the ship each day to see what else they can find. The man's cough worsens and then the boy gets sick, too. The man believes the boy will die and he is terrified and enraged. The boy, though, recovers.
The man and boy decide to leave their camp on the beach, and they pare down their food stores so that the cart is more manageable. They hike up and down the shore, and when they return to their camp they see that all of their belongings have been stolen. They take off after the thief and find him. The man makes the thief take off all of his clothes, leaving him there for dead, which is what the man tells the boy the thief did to them. The boy begs his father not to hurt the man, and when they leave the boy cries and convinces his father to take the man's clothes back to him. They can't find the man, but leave his clothes in the road. The boy tell the man that they're responsible for that other man, that they killed him, and it makes the boy question their role as the good guys. He says they should be helping people.
They walk through another barren town, and the man gets shot in the leg by an arrow. He shoots a flare through the window from which the arrow came and hits the man who shot him. It's unclear whether he kills the man, but when the boy asks, his father tells him that the arrow shooter lived.
The man stitches up his leg and they press on. The man grows weaker, his cough worsening and becoming even bloodier than before. The man's dreams soften and he knows he's going to die. They make camp and the man tells the boy not to cover him because he wants to see the sky. The boy brings his father water, and the man sees a light surrounding the boy. The man tells the boy to go on, to leave him, but the boy refuses. Eventually, the man dies. The boy stays with his father's body for three days, then a man with a shotgun finds him. The man invites the boy to come along with them. The man says that he's one of the good guys and that he's carrying the fire, too. He also says that they've got a little boy with them and a little girl, too. Eventually, the boy decides to go, but not before he says goodbye to his father. The boy leaves his father covered in a blanket.
The novel ends with the boy welcomed into a new family in this new world that he must learn to inhabit. The question of his future, and the future of humanity remains. The boy talks with the woman about God, and he admits to the woman that it's easier for him to talk to his father instead of to God. The woman tells the boy this is okay, because God's breath passes through all men. The final passage of the novel is set up in story form, evoking thoughts not only of the man and boy's story, but also of humanity's story as a whole. The novel ends with a note of mystery — the mystery of the bond that exists between father and son; the mystery of the boy's and humanity's future; and the mystery of this new world and what it will be like now that it has been forever changed.