The Secret of the Mansion

I finally get to read the first book in this series!! I've read other stories, but I never actually knew how the main characters met each other or anyone else. A great example of how, in older kids books, any random group of kids just start solving mysteries if they get a full series. I must've been born too late, cause clearly in Ye Olde Times, adults just turned to the nearest preteen and had them solve whatever weird thing was happening.