After escaping the city, Montag comes across a group of seeming hobos living outside on the railroad tracks. After they watch the government pretend to catch Montag on a portable TV, the leader, Granger, explains their mission:
"All we want to do is keep the knowledge we think we will need, intact and safe... We'll pass the books on to our children, by word of mouth, and let our children wait, in turn, on the other people."
(Bradbury, Fahrenheit 451, Google Books)
He and the others memorize books and try to pass them on to other people. When the war is over, Granger hopes to use his people to reintroduce the ideas and knowledge in books to society. Although he knows that they cannot save every book this way, he hopes that their work will keep humanity from falling into a Dark Age of its own creation. Montag chooses to join them, walking the railroad tracks; it is the first truly independent choice he has ever made.