Trixie lives on a farm in New York. Honey is her best friend who lives in a mansion next door. Diana is another one of their close friends. They have a club called the Bob-Whites of the Glen that also includes many of their siblings. They often find themselves mixed up in mysteries and adventures. Because they are younger than Nancy Drew and the Hardy Boys, actually around the age of 13, their adventures are somewhat toned down. You can almost call Trixie the younger and more realistic version of Nancy Drew.
Only 39 adventures were ever written in the series. The first 15 are the only ones currently in print. I have numerous copies of the older ones, thanks to my cousin. They are not too scary, making them a great read for elementary students.