A father and his son travel on foot to the southern coast, seeking a warmer climate in which to live out their days. A few months before the boy’s birth, an apocalyptic event ended civilization and scorched the entire planetary ecology, leaving behind a vast cloud enveloping Earth. Even though years have passed since that event, the son has never seen the sun, moon, stars, or living plants and animals. Father and son wear masks to filter the pervasive ash particulate residual from the disaster.

Father and son share a deep bond of love and a commitment to each other. Their survival plan depends on constantly moving along the road while scavenging food, clothing, and supplies from the ruins of homes, farms, and towns. As they move south across the cold, gray landscape, the father and son encounter the spectrum of humanity, ranging from goodness to depravity. They struggle to preserve memories and values that are becoming increasingly meaningless in a world where the future was wiped out with the past.

The story begins with the father and son journeying through the mountains, pushing a shopping cart containing all their belongings: food; supplies such as tools, blankets, and tarps; and toys to pass the time. The father suffers from a worsening respiratory condition, which causes him to cough blood. While the father and son peacefully search what’s left of civilization for their sustenance, other survivors resort to depravity. In the absence of agriculture, animals, and technology, cannibalism has become widespread. Road agents and cults hunt other travelers and keep women as slaves to produce babies for food.

The father and son constantly watch out for the armed marauders, the father reserving the last two bullets in his pistol for themselves. Persevering through terror and starvation, they find the treasures left by people who planned for the future. A plantation home situated in the middle of vast farm fields, visible in the ashen mist only to young eyes, yields bounties of food and healthful amenities. A farmhouse with an abundantly stocked underground bomb shelter provides a refuge when most needed. The wreck of a sailboat provides a first-aid kit and a flare gun that save the father’s life.

Encounters on the road test the father’s and son’s mettle and shape their character. The father sees threats and becomes hardened: He shoots a road agent who puts a knife to his son’s throat, and he withholds food from unfortunate people they meet. The son sees the needs of other people and develops compassion: He grieves for a man struck by lightning, a basement of prisoners held to be food, a disillusioned old man traveling alone, a dead baby, and a thief with a ruined right hand. When the son sees a young boy—his mirror image—he wants to take the young boy with them. The son comes of age on the road, forming his own conscience apart from his father’s choices. Nothing defaces the empathy and goodwill that he wears for the world to see.

Eventually, the father and son reach the coast, but the walk has broken the father’s health. On his deathbed, he breaks his promise to his son to never leave him: He doesn’t have the heart to use one of the remaining two bullets to shoot his son and hold him dying in his arms. The son asks the father what he will do without him, lost and alone. In his last words to his son, the father tells him that goodness will find him. 

The son wraps his father’s body in blankets and sits with him for three days. Then he goes back to the road with the pistol in his hand. A man comes over the crest of the road and kneels down in front of him. The man asks the son if the man he saw the boy with is his father. The son tells him yes and that his father is now dead. The man invites the son to join him, his wife, and their two children. The son questions the man about his standards, and the man assures him they are the good people who do not eat others. The man wraps the father’s body in a blanket, and the son mourns next to his dead father for a long time before departing with the man. The wife welcomes the son with a joyful hug, expressing her gratitude that he is now with them.