In 1975 I read a young adult novel about a city boy sent to stay the summer at his grandmother’s house in a small town. He doesn’t want to be there and expects to have a boring time, but stumbles across a mystery that he decides to solve. None of the adults in town believe him, but he eventually solves the mystery with the help of an older, wisecracking boy from the town. I don’t remember any details other than that the town was very small and along a small river or large creek and his grandmother’s house was at the edge of town near the river. I think the story was set in the generic “midwest” or “northeast”. The book was probably written in the mid- to late 1960s or early 1970s. I don’t think it was part of a series.
It sounds like we are looking for the same book and one I would very much like to find! I recall reading this book around 1976. It was purchased from a Scholastic book flyer at school. It may have had an orange and black cover. The plot revolved around an old unsolved murder in town and the boys set about investigating it. Eventually they find a gun hidden in the rafters of a barn. I think the barn might catch on fire in the end. Does any of this sound familiar? Let’s get this “stumper” back to the forefront and get our mystery solved!