A religious fanatic (and minion of Satan), he is the main antagonist of the film. His aide-de-camp was Malachai Boardman. During a drought he led the children of Gatlin, Nebraska in a massacre of the adults there. After that they were taken to the cornfield so that the crops would grow again. Isaac then presided over the cultist-orphans and their town. During the next three years everyone who became adult was sacrificed while everything modern and different was destroyed by him, too. Unbelievers with the exception of Sarah and Jobe were also killed. Malachai executed that for him. However dissent started to grow between the two in time, fueled by Sarah and Job.
All changed, when Burt and Vicky casually arrived there three years later. Their arrival triggered the dissent between Isaac and Malachai and Isaac was in the end sacrificed to "He Who Walks Behind the Rows" by a jealous Malachai. However, he was sent back by him in a more demonic form. As such, Isaac strangled his treacherous henchman. When Burt - aided by Job and Sarah - defeated the cult and set the cornfield ablaze, Isaac and his hellish master were dispatched to "the Lake of Fire" once again.