Here's a breakdown of what happened:
* The Old Lady's Refusal: Montag was sent to burn the old lady's house because she refused to leave her books.
* The Secret Room: When Montag entered the attic, he discovered a secret room behind a wall. This room was filled with books, hidden from the firemen and the society.
* The Old Lady's Sacrifice: The old lady refused to leave the attic with the books, choosing to die with them rather than give them up. This act of defiance shocked Montag and planted a seed of doubt about his society's rules.
* The Spark of Rebellion: The discovery of the old lady's hidden library and her self-sacrifice marked a turning point in Montag's journey. He realized there was more to life than burning books, and it sparked his desire for knowledge and understanding.
This scene is pivotal in Ray Bradbury's novel *Fahrenheit 451*, as it sets Montag on his path towards rebellion and the pursuit of knowledge.