A girl named Sally lives on a farm in Kansas with her family. It is the 1930s, and dust storms and poverty plague the family. One of Sally's siblings, Ben, is fourteen and ill from the dust in his lungs. The animals on the farm are also dying, and Sally's father kills a dying calf and splits it open to find its insides covered in dust.
One day, two men come to the house that Sally thinks are government men. They go to talk to her father. When Sally comes inside, they are talking about the Dubort place, which the children call the Devil's Garden. A meteor had fallen one day onto the farm, and then large vegetables and vegetation had started to grow. Mr. Duport brought a vegetable to their house once, but it was filled with dust. Mr. Duport had disappeared, but they had found a creature that looked like him at a neighboring farm, and Sally's father and other men had said they would do what needed to be done.
Now, the two government men want Sally's father to take them to the Duport place, and they offer fifteen dollars for the tour. Although Sally's father and mother are scared, they agree because they need the money. A few hours after Sally's father leaves, a dust storm comes in. Sally's father still has not returned. They family goes to church, and they are sure Sally's father will be there, because he never misses church. Sally's mother tells the man who found the Mr. Duport creature on his farm, and the men all decide they should organize a search party. The older of the two government men shows up in town, yelling gibberish with his eyes rolled back in his head. Sally decides that she needs to find her father, so the next morning she tells her mother that she is going to school and leaves.
Sally goes to the Duport property, and there is no noise or animals, but there is greenery everywhere. She finds cans of gasoline and the younger government man's hat in the center of a crater where nothing grows, which is where the meteor hit. Sally feels like she is being watched. She finds the house, and goes inside, where it smells like rot. She hears wheezed breathing, and lights a match to see what it is. She finds vines coming out of a bulky mass in the wall that has her father's face and a cuff link from the government man and is a jumble of organs and plants. The creature reaches for Sally, and she runs out of a window, cutting her knees in the process. The creature stops to drink her blood, which saves her. She runs away from the property.
Once she is a safe distance away, Sally decides that she needs to do something so that others won't die. She returns to the clearing and retrieves the containers of gasoline, and then she forces herself to walk into the house. The creature is not in the same spot, so she ventures further into the house. She finds a ladder going down to a cellar, and climbs down to discover a room of vines, plants, animals, and humans all merged together. The vines move forward towards Sally and dig into her legs. She finds the section of the creature where her father's body is, and throws the gasoline at it, and then a match. She tears vines off of her skin and runs out of the house to safety, the vines screaming inside. 
Sally is found by her mother and other adults on the road. She has a fever for a while and misses her father's funeral, but she is finally allowed to come home. The family is in financial crisis, because the hardware men are calling in their debts since Sally's father is dead, and they have many unpaid bills. Sally's mother decides they will stay on the farm, because it is what Sally's father would have wanted. Sally imagines the future, where her baby sibling is dead from the dust and the land is foreclosed, and the future is more scary than the creature she encountered. However, she stays positive for her mother's sake.