Millie Two Bears, a middle-aged woman, lives alone in a trailer on her husband Arthur’s family farm in rural Montana. The land is part of the Blackfeet Nation Indian Reservation, of which Millie and Arthur are members. Almost a year ago, Arthur was sentenced to twenty years in prison after he hit and killed two schoolchildren with his truck while rushing home.
 One day, Millie notices a strange hole in the ground. She realizes that it is a prairie dog hole, and that many such holes have popped up around the place. While she is out in the morning putting poison pellets in the holes, a woman arrives. She introduces herself as Frog and says that she wants to rent Millie’s extra camper, and Millie agrees. Eventually, Millie has an uncomfortable conversation with Frog where Frog reveals that she knows about Arthur’s crime. Millie goes to shovel dirt into the prairie dog holes, and offers Frog free rent if she’ll help, but Frog refuses, saying that she can’t do it. Millie spends the next few days plugging the holes, only to find them burst open again. Millie notices that Frog behaves abnormally and seems to be watching her.
Millie goes into Frog’s camper and finds it littered with hand-drawn sketches of the prairie dog holes and a drawing of Millie labeled “KILLER.” Millie has two men come to the farm and shoot the dogs to put an end to the whole situation.
Millie gets the impression that Frog knows what Millie is going to do next to take care of the prairie dogs, and asks Frog what she’s really doing there. Millie tells Frog that she thinks Frog is a relative of one of the children that Arthur killed, and that she has come to the farm to threaten and scare her. Frog denies this, but ominously asks where Arthur washed the children’s blood off his truck.
Millie sneaks into Frog’s camper and finds a mysterious, futuristic-looking radio device. She looks around and sees more sketches of scenes from the past few days, but discovers that they are actually printed-out pictures. Terrified, Millie accidentally falls through an opening in the floor and into a prairie dog hole. She sees it crusted with blood, and finds a disembodied hand clinging to the edge—Frog’s hand. She looks up and sees a large drawing of a tentacled monster on the camper ceiling. Millie realizes that Frog is from the future, and has come back to see the prairie dog-monster in its infant form. In the future, the monster will grow huge and powerful, and when time travel is invented, people like Frog will go back in time to see where it all started. Millie realizes that Frog has unknowingly altered the future by traveling back here.            
 She goes outside and sees tentacles emerging from the ground. The monster soon pushes something up from one of the holes, and Millie realizes that it is her old injured horse who later died. Millie suddenly understands that the monster can recreate living things by getting their DNA from the soil, and it soon pushes up new versions of the two children who Arthur killed, as he had washed their blood off onto the land. She runs inside and grabs Arthur’s old coffee mug and gives it to one of the prairie dogs. She goes home and gets in bed, and feels Arthur get into bed next to her.