The Light in the Forest is about the struggles of a White boy, John Butler, who was taken captive as a boy in Pennsylvania by the Lenni Lenape Indians and became assimilated.
The story opens in the autumn of 1764. John Butler, approximately fifteen years of age, has lived with the Lenni Lenape in Ohio since being taken captive eleven years earlier. His adoptive Lenape father, Cuyloga, renamed him True Son. He is assimilated and accepted as a full-blooded Lenape by that community. Along with other Native groups, the Lenape enter into a peace treaty with the British forces. The treaty required that the Indians had to return any White captives. True Son did not want to leave as he was fully assimilated and considered himself Lenape; he disdained White society. He tries to commit suicide in order to be free of the Whites, but is unsuccessful. Accompanied by a young soldier, Del Hardy, True Son is taken to Fort Pitt, where he is met by Harry Butler, his blood father. Hardy accompanies the Butlers to their home in Paxton Township, near present-day Harrisburg.
After returning to his father's home, True Son refuses to recognize his blood father, continues to wear his Indian clothes, and pretends that he no longer understands English. His younger brother Gordie is intrigued by his Indian ways and True Son becomes fond of him. Later, True Son gets into a heated argument with his Uncle Wilse. Wilse accuses the Indians of scalping children, which True Son denies. Wilse is so angered by what he perceives as the young man’s lack of respect that he slaps True Son.
That spring True Son develops an unidentified illness. His physical sickness is compounded by disappointment that none of his Lenape family has tried to contact him since he was forced to go to the Butlers. He is heartened by learning that two Indians were asking about him at Wilse’s shop. That evening he slips out of the Butlers’ house and discovers his Lenape cousin, Half Arrow, nearby. Their reunion is tempered by learning that men from Wilse’s shop shot and scalped their friend, Little Crane.
The boys confront Wilse, knocking him to the ground and scalping him. They escape the town into the forest and head west to return to the Lenape. Their people are angry over the murder of Little Crane, and eventually the tribe declares war on the Whites. They attack some small villages and scalp the settlers. True Son sees some children's scalps among the rest and is disturbed to learn that the Indians killed children as well as adults.
True Son is used as bait to lure a band of settlers into an ambush, but he gives away the plan when he sees a child among them who reminds him of Gordie. The Lenape are enraged and plan to burn True Son at the stake in ritual torture. His adoptive father Cuyloga convinces the other band members to banish his son. Cuyloga tells True Son that he is no longer Indian, that he would be considered as a White enemy if ever seen again in Indian territory, and that he (Cuyloga) is no longer True Son’s father. Cuyloga accompanies True Son to a White road, where they part.