Final answer:
Isabelle and Hugo came across the story of Prometheus in a book of myths and in a painting located in the film library, as connected with Orozco's murals described in the provided information.
Step-by-step explanation:
Isabelle and Hugo encountered the story of Prometheus in a book of myths and in a painting in the film library.
The reference to Prometheus in the film library connects to the information provided about the murals painted by Orozco - notably the mural at Pomona College in Southern California titled Prometheus, and The Epic of American Civilization at Dartmouth College in New Hampshire.
These artworks deal with themes related to Prometheus, such as the impact of knowledge and enlightenment on humanity, which are integral to understanding the myth of Prometheus.