I only really remember the only one I owned, which was the one where Wanda (? tree-climbing girl) has her Japanese penpal come for a visit, and she turns out to be a ~super-amazing detective~ and everyone has to A) foil a dastardly kidnapping plot and B) put up with McGurk's increasingly and ridiculously petty attempts to prove that He Is The Best Detective Here Thank You Very Much, and also karate. The rest of the series... I remember something about a lost turtle. And the narrator typing a row of 7s over a row of 8s on their typewritten business cards so they would look all fancy and interesting.