Who does Montag find, or rather, who finds Montag?I believe this may be in Section 3 of the story.

If you are talking about what happens in Section 3, then
the answer is that Montag finds (or is found by) a group of men who call themselves
"book covers."  They are led by a man named Granger.

These
book covers are people who have decided to leave the society behind and go out to the
country.  They cannot stand the way that people are forced to live in the society.  Each
of the men has memorized a book or part of a book.  They are hoping to keep those books
"alive" until something happens that will let them come back to society and try to help
it.  They hope to remake society some day using the ideas from the books that they have
memorized.