It may have been published in 1980s/early 1990s, maybe on a Scholastic list, set in the 1800s, a boy visits his ?aunt/uncle one summer, on a farm or apple orchard in New England (maybe Pennsylvania). There is a secret passage used for the underground railroad that is discovered by the boy in the house he is staying at, near the end of the book, when someone is hidden there. Someone may have gotten shot near the end of the book. Boy felt aunt/uncle he was staying with were strict and had a strained relationship with them until their aid to this person near the end of the book changes this. Can't recall the title, but it was long-ish. Cover may have had farmhouse/farm landscape.