It’s no secret that I love investigative adventures (heck, you only have to go this  far back to know that!). I like playing them, I like running them, and I like writing them. That said there’s a lot of prep that has to go into building a mystery adventure and I thought I might share some of the tips I’ve come up with over the years. This is the first installment of a series of articles on writing mystery adventures.
Know what’s on the character sheets
So where to start? The first step on writing a good mystery adventure is to know what’s on your player characters’ sheets. Seriously, take a look at them, even if you think you know what’s on them. I can’t tell you the number of times a mystery adventure was cut short because a PC whipped out a power I’d forgotten she had (especially in campaigns where magic items are handed out like candy) or slowed to a crawl because the player with the private investigator character forgot to buy skill ranks in “Search” (don’t laugh; it’s happened).
Prepare for troublesome powers
There are many powers that can short-circuit an adventure if you don’t account for them. Mind Reading (“what is the bellboy thinking when I mention the gun being found in the trash can?”), Object Reading (“who was the last person to touch this bullet?”), Postcognition (“what happened in this room last night between 12 am and 1 am?”), and Speak with Dead (“who killed you?”) can out the culprit in a matter of seconds.
All of these powers can be worked around, but you have to be careful here, too. If you constantly nerf a PC’s power then it’s better that you outlaw the power from the get-go rather than make the player frustrated every time she tries to use something she gained legitimately. If this is a new campaign that is focused on mystery-solving, go through the list of powers and weed out the most problematic ones for you. Some of these you’ll want to ban outright; others can be tweaked so as to not be so powerful (reading emotions instead of thoughts or getting symbolic images or a static snapshot in time rather than “real-time video” of the past).
If your mystery adventure is simply a change of pace for an ongoing campaign, then my best advice is to work around the PCs’ troublesome powers as best you can. Players tend to be more forgiving if they only lose the use of a power once or twice.
Make sure the characters have the necessary skills
Similarly, you’ll want to take a look at the characters’ skill sets. Building a character for a mystery-focused campaign is very different from other campaigns (ask Call of Cthulhu players how handy those massive combat skills are against alien races and old gods). Again, if this is a new campaign you can offer guidance (“okay guys and gals, this is the short list of necessary skills; make sure you each have some ranks in them), but in an ongoing campaign you’ll want to write the mystery adventure to play to the PCs’ strengths. Don’t penalize them for not having skills that didn’t seem all that important when you pitched the “pulp heroes fighting against the Diesel Emperor’s air fleet and mechanized minions.”
In short, while you want to hook your players and get them excited about tracking down clues and suspects, make sure that the adventure is a challenge for the characters involved.
I hope all of you American readers have a Happy Thanksgiving this Thursday! In the next installment, we’ll take a look at hooking the characters.