In 1893, Katherine Comstock talks about her unborn child with her neighbors Margaret and Wesley Sinton in Indiana. On his way home that evening, Robert, Katherine's husband, stumbles and falls into a pool of quicksand while following a path through the Limberlost marsh. Katherine sets out to assist him in the marsh, but by the time she gets there, she is powerless to save her husband's drowning. Later, following the birth of the kid, called Elnora, Wesley and Margaret are spotted holding the infant while talking about how unfortunate Katherine is that she does not like her new daughter. Wesley adds that Elnora is the last thing Katherine has left after her husband passed away, but they hope they could keep the baby if Katherine does not want to retain her because they recently lost a child of their own. After a while, Phillip, Dr. Ammon's nephew, pays the Sintons a visit and shows interest in Elnora. He urges her to use the money for her education expenses and offers her money in exchange for the Indian antiques she has been collecting. Later, in order to expand her collection, they go into the Limberlost and chase moths. He mentions that he was leaving town that evening and that he was seeing his fiancé, Edith, back home in Washington. They pledge to keep in touch after they part ways. In a letter to Phillip in June 1913, Elnora informs him that she has saved up enough money to cover her college expenses and that she no longer requires his assistance, as he had previously assured her. She discovers, however, that her money hoard, which she had stored in the swamp tree, has been taken along with her collection of moths. Although her mother offers to locate a dress for her herself, Elnora is upset that she lost the money she had been saving, particularly because she had intended to get a new dress for her upcoming graduation. Elnora learns, however, that her mother did not receive the outfit as promised on the day of her graduation. Elnora leaves for Mrs. Parker's after a fight, where she is offered a graduation gown. Katherine, who is visibly concerned that her daughter is turning to others for assistance rather than to her, observes from across the street as the two go to Elnora's school together for the ceremony. Billy, who she encounters on her way home, informs her about Elnora's financial loss and that he believes he knows who stole it. Katherine searches the suspected criminal's home but is unable to locate him. Rather, she discovers an ailing woman who, she finds out, had an affair with her husband Robert until his passing. When Katherine finds Elnora in Mrs. Parker's house, she begs her for forgiveness for treating her so badly for a man who never loved her as much as she believed. As Elnora forgives her mother, they get back together. Phillip and his fiancée Edith return to town when they get home. The following day, they invite Elnora to a party that Phillip's uncle is hosting for them. Her mother persuades her to go despite her initial reluctance. Edith is upset with Phillip for talking about Elnora the entire night at the party. Later that evening, Phillip and Elnora reunite and pursue a yellow emperor moth they had previously been searching for into the Limberlost. After a brief conversation during which Phillip leans in to give her a kiss, they decide to return to the party. They both deny it, but when they return, Edith accuses Phillip of having an affair with Elnora. Phillip visits the Comstock home the following day to inform Elnora that he and Edith had called it quits on their engagement and that he would want to date her. Elnora declines him and confesses her shame, believing she is the cause of their breakup. In the midst of the Limberlost, Elnora sobs to herself about her mixed emotions, saying she no longer gives a damn about her moths, college, or anything else. When Phillip searches the Limberlost for her, he discovers that she has fallen into a mud pool. At the end of the film, he takes her out and they embrace. Elnora is an adolescent in the story's flash forward, which takes place many years later. When Elnora informs her mother that she is attending high school, Kathrine first objects, preferring that her daughter stay at home and take care of the housework. Elnora makes a halt at a tree in the Limberlost swamp on her way to school, where she has been keeping some of her possessions, such as a collection of moths. She is taunted by her classmates once she gets to school, which makes her not want to go back the following day. Later, she goes to see the Sintons, who offer to help her buy the books she needs for class and encourage her to stay positive. Katherine still mistreats Elnora at home and accuses her of being responsible for her husband's passing. Elnora witnesses a small boy named Billy trying to steal from a person's house on her second day of school. She offers him some of her lunch after they settle down. Elnora goes to see Mrs. Parker, referred to as "The Bird Woman" in their neighborhood, after school. By giving Elnora the woman's name, the Sintons informed her that she would be able to assist her. Elnora runs with Billy again on her way home, and he informs her that his father is too unwell to walk or speak. When they get at his home and discover that his father has passed away, Elnora brings Billy to the Sintons for assistance. Billy is ultimately taken in by the Sintons to be cared for by them.