The current arc in a game I play in revolves around social intrigue. Briefly, the spurned mentor of a young king has asked the party to help unmask a quartet of self-interested nobles who have been pushing the king towards starting an ill-advised war. We're trying to uncover why they want war so much, how they're going about it, and how they would benefit from its outbreak.

The longer this goes on, the more I realize that this kind of game is substantially more difficult than your basic dungeon crawl. As a player, I have found myself struggling to think of things I could do to help advance the party's goals without immediately blowing our cover. Amazingly, I'm not a covert agent, and I have never actually tried to intervene in the politics of another nation. I have no previous experience to draw on when doing so in-game, which makes it ... challenging.

Looking at it with a DM's eye, it appears difficult to run. You have to strike a balance between the NPCs taking believable actions to protect their secrets, and allowing scope for the PCs to uncover them. As with mysteries, it's easy to put in clues that are too obscure, or too few in number, resulting in the party going of on some wild tangent based on a cocktail of incomplete information and incorrect assumptions. But if you make things too easy, there's no tension, no sense of accomplishment. Judging the correct level of challenge is tricky, because much of it falls to player ingenuity rather than PC mechanics.

To those of you who have played this type of game before: what tips do you have for doing intrigue well? What should we do to make it work smoothly? What pitfalls should we avoid?

I'm equally interested in hearing from both player and DM perspectives.