In August, a woman and her sister Bobbie drive and listen to cassette tapes. The woman recalls when she and her sister drove through several southern American states. As she shifts in and out of reality, she speaks to Bobbie as her lover, encouraging her not to close her eyes. The woman thinks of other times on the highway. She continues to call Bobbie 'love' and again urges her to open her eyes.

The woman begins to recount the time she stopped at a rest stop near Shreveport. Here she picked up a girl in a red baseball hat. Bobbie says that picking her up is going to be memorable. The three of them share stories. The girl in the hat says the pair who picked her up are twins. They respond yes that they are twin sisters.

One of the twins thinks she can turn the girl inside out and that it has been over a week since they last murdered someone. The same twin thinks about how over the past week, she and her sister just drove, ate junk food, and had sex with each other.

The first twin remembers their next murder. The twins have sex with each other while brutally murdering a man they name Thin Man in a cornfield. Back in the car, twin one continues urging her sister Bobbie not to sleep. In her memory, after they murder Thin Man, twin one consoles Bobbie who sobs.

Twin one remembers a time she picked up a man who had never seen the ocean. Bobbie has sex with him. Twin one slits the man’s throat. Bobbie is upset that they didn’t at least show him the ocean.

Twin one again urges Bobbie to stay awake.

Twin one remembers a time they picked up another girl at a truck stop who threatens to shoot them after they pick her up. She tries to steal the car. The twins murder her and abandon their car. This is the only instance in which they ever kill someone in self-defense. They steal a car and make their way to a gas station. They take the girl’s gun with them.

After cleaning up at the gas station, Bobbie accidentally shoots herself by the gas pumps. Fearing an explosion and arrest, twin one takes Bobbie and drives endlessly down the highway. Twin one calls Bobbie by her name, urging her not to go to sleep.