What happens in the house behind closed doors? What are some of the secrets from the story thus far? How might the secrets affect the story?
You will need to clarify this question. Are we talking about the Radley house, where Boo is alleged to have been kept for years, or are we talking about the Finch house, where Scout says Atticus behaves just as he does on the street?
In the case of the Radley house, neighborhood rumors and gossip have surrounded it with an air of mystery. Miss Stephanie Crawford, among others, has told tales of how Boo Radley was kept in the courthouse basement instead of being sent to an insane asylum, and that when he returned home, he was restrained into his bed.
Other tales persist about how Arthur "Boo" Radley allegedly stabbed his father in the thigh with a pair of scissors, and the populace's general impression of the Radleys is one of distrust and confusion. Because they are socially reclusive, no one in Maycomb has many positive things to say about the Radleys or their house.
In the case of the Finch house, Scout tells Miss Maudie Atkinson that Atticus never does anything inside their home that he would not do in their yard or outside. Miss Maudie believes her, and as the story develops, we see the even-tempered nature of stern Atticus Finch demonstrated.