Boo Radley is thought to be a "malevolent phantom" at this stage in the book; that is, rumors have circulated about him being a criminal, a madman, a stalker, and other unkind labels. It was also rumored that he was kept chained to his bed by his father, Nathan Radley.
With all of this information, Scout and Jem's curiosity about the Radley place is great. So, when Atticus returns from a trip to the home that generates such interest, Scout asks him about the state of affairs within the house to try and ascertain just exactly how things truly are over there. Atticus is the picture of forthrightness throughout this novel, and Scout knows he can be relied upon for an objective account.
Scout has heard all kind of rumours about Boo Radley and she wants to check her father's version against that of such people as the town gossip Miss Stephanie Crawford.
According to local tales, Boo is a drooling maniac, a peeping Tom, prone to violence (as when he stabbed his father in the leg with a pair of scissors). He also eats raw squirrels and prowls around at night, much like a nocturnal animal. All of this is interesting enough, but even to Scout, these stories have a hollow ring....
Scout knows her father is an honest man, not given to exaggeration or gullible enough to fall for 'tall tales.' She wants to get more reliable information from a more reliable source. So she pops the question to Atticus since she knows that is the best place to go.