Or Home Alone for Nerdy Kids. This is a quickie because I haven’t actually reread it. I’ll try to summarize from memory and then you all can fill in the blanks. Two sisters, somewhat whiny, are on a trip with their parents and they stop at a small time library. While looking around, the library closes with them in it. And this is scary? Imagine being locked in a library with nothing to do but browse all the books with no one to bother you? I am sure that for 98% of us reading, that sounds like heaven.
Instead of freaking out, for some reason I remember them dressing up in prairie clothes and sitting on a covered wagon with life sized paper mache people to pass the time. What? Why? Eventually they find that an old woman lives upstairs at the library and she almost dies but they save her.
I also remember these sisters being extremely high maintenance and annoying. And they are always finding themselves in trouble. I think there is a sequel in which they are almost beheaded at an amusement park.