Locked room mysteries are always resolved by the end of the book. There's no ambiguity about the ending. The author presents a puzzle and the reader has the opportunity to solve it as he/she reads the book and learns additional facts about the setting and the personalities, but even if the reader can't figure out the puzzle, he/she knows that all will be revealed by the end of the book
It's sort of as comforting as a warm cup of cocoa on a cold winter's night.
