The Wolves of Steadwick is a module in which the players are to solve several mysteries. Combat is much less likely to be the solution each time so let them know ahead of time that there will be an overarching mystery and to keep focused to get clues.
Maps, NPCs, custom creatures, even a random peasant name generator. This 55 page module is in depth and difficult. Each file is created for use with the stated edition. You can get all 3 for the price of 2 if you are unsure which edition you will want the file in.