Stories and Hidden Plots

[JohnDurvin]

Okay, not having taken a lot of formal writing training, I'm not sure what the terms are for what I'm trying to talk about, but I'd like to vent. There's a problem I've seen in a few different books (currently the first half of "The Dark Lord of Derkholm" by Diana Wynne Jones, all of "Muddle Earth") where there's a sort of "secret plot" going on behind the scenes, and the protagonists are kept totally in the dark about it. The problem is, the author put too much effort into that aspect of it and neglected the part of the story that we're actually getting to read, and it seems like it's nothing but inexplicable events, cryptic chats, and subtle hints that are obviously hints to something but we're not given enough to really feel like we need to solve the mystery.

In the case of "Derkholm", I love "The Toughpick Guide to Fantasy Land", so I was curious enough to soldier on until things started to get actually going, and now I'm loving it. As for "Muddle Earth", well, there's probably a good reason not many people have heard of it; it was an obvious knock-off of "The Hitch-Hiker's Guide to the Galaxy" with a tacked-on attempt at a plot that wasn't altogether successful. The "hidden plot" bit has been used pretty expertly by a lot of different authors (all mysteries, for example). So has anybody else noticed this problem in other works? Tips on how to balance the main narrative while hiding the real story?