The last book in the introductory trilogy. We get to meet the Trixie's brothers who have come home from working at summer camp. This is also the book where the Bob-Whites of the Glen (the club all of them belong to) gets established.
How I wished that I could have belonged to their club. Five teenagers who get along with each other and have adventures. How cool is that! ( )

The gate house mystery is a real page turner and also very mysterious :) ( )

Loved it...owned this one too...don't know where it went ( )

As summer draws to a close, Trixie Belden and Honey Wheeler decide to transform the Wheelers’ ramshackle gatehouse into a secret clubhouse. But when Trixie’s little brother (literally) stumbles upon a diamond buried in the gatehouse threshold, the girls once again find themselves up to their elbows in mystery and mayhem.

Convinced the diamond is part of a pickpocket’s loot, Trixie turns bloodhound, obstinately refusing to be dissuaded by Honey’s sensible adopted brother, Jim Frayne, or her own brothers, Brian and Mart, who have recently returned from their summer jobs at a boys’ camp. Eventually, of course, the boys begin to see things Trixie’s way as the cat-and-mouse game with the Wheelers’ mysterious new chauffeur heats up.

The Gatehouse Mystery is the last of the series’ “introductory” novels. With Jim, Brian, and Mart at last firmly ensconced in the plot, the wisecracks and good-natured sibling rivalry—trademarks of the series—fly full force. The relationships between these five teenagers provides the foundation for this grand old series, and from the third book on, it doesn’t miss a step. ( )

I loved this series when I was growing up; I thought Trixie was a lot more fun than Nancy Drew, and these were some of my all-time favorite books. I read them as an adult, though, a few years ago, and found that they haven't, IMO, stood the test of time well. They are obviously dated, and there are some messages that I don't think are appropriate anymore (mostly the way Trixie is treated differently - and often poorly - because she's a girl). ( )