On a sweltering summer day in the sleepy town of Mercer, a comically hellish odyssey begins for easygoing gas station attendant Clay Bidwell. While drinking beers and shooting for target practice in the woods, Clay's best friend, Earl, turns his gun on Clay and accuses him of having an affair with his wife, Amanda. Before Clay can react, Earl shoots himself in the head in an effort to frame Clay for his murder. Clay manages to cover up the mess, but the the level of callousness diplayed by Earl's widow and his lover, Amanda prompts him to dump her. When Amanda catches him in bed with another woman, she plots a venomous revenge.