Jem, Scout and Dill are afraid of Boo Radley. They believe in the rumors surrounding the reclusive and mysterious figure. Repeating stories heard in the neighborhood and combining them with a sense of superstition, the three children build up an image of Boo Radley as a dangerous man, prepared to do violence at any moment, capable of eating squirrels and other creatures, and generally frightening.
A local legend for several years, Boo is rumored to wander the neighborhood at night and dine on raw squirrels and cats. He has spent the last fifteen years secluded in his own house.
To their credit, the children also harbor a conflicting view of Boo Radley at the same time, believing that if Boo would come out and meet them, he would feel better knowing that people like Jem, Scout and Dill would be kind to him.
Given these two conflicting views of Boo Radley, the children have fun believing in the more ghastly view of Radley.
The children are naturally afraid of and intrigued by such a "malevolent phantom," as Scout calls him.
To test their courage, Jem occasionally enters the Radley yard to retrieve things that have gone over the fence. He also is dared to touch the house and feels he cannot refuse the dare.
Jem goes through with the dare, running through the yard to touch the house and running back out as fast as he can. Later, Dill and Jem hatch a plan to peek in a window of the house to get a glimpse of Boo Radley.
They do this at night with nearly dire consequences.
...they attempt to look in the house to see Boo, but a shotgun blast from Nathan Radley, Boo's brother, drives them off.
The children refrain from more tests of this kind while they also begin to learn that leaving Boo Radley alone is the right thing to do in order to respect his privacy.