I was reading this article on investigative adventures in D&D on Sly Flourish. Very interesting, especially to me right now, since in my campaign we will start an adventure like that next Monday. In the past, and with a different DM, we had adventures in which the players were supposed to investigate go wrong and stall, so this is kind of a danger zone for us. I think it helps to consider some human aspects here, starting with expectations.

We've all read or seen detective stories, from Agatha Christie's Hercule Poirot to Inspector Colombo. Being familiar with the format evokes a certain set of expectations when you try to play through something similar. But the detective in such stories cheats. There is only one author who controls both the murderer and the detective, so the detective can't fail to find all the clues, in the right order, and to put together the pieces to come to the right conclusion. The moment that you turn that into an actual multi-player game, with the DM having set the scene, knowing who the killer is, and having set up the clues, while the players need to discover all that, there is a significant chance that the players won't end up as successful as a Hercule Poirot.

The first advice here, based on own experience, is that a played murder mystery has to be significantly less complicated than one from a book or TV show. There need to be less locations to investigate, and less witnesses to question. That is especially important for a group like ours, as we only play twice per month maximum. If it takes us 6 sessions to investigate all locations and speak to all witnesses, that means that by the time we finish with the last, we have already forgotten the clues from the first, which was 3 months ago.

The advice from Sly Flourish is related to that: The players don't usually know where the clues are, and might well investigate a location that you as the DM didn't foresee, or talk to an NPC that you hadn't considered in your murder mystery. If the adventure doesn't limit the number of locations and NPCs somehow (murder in an isolated location like the Orient Express, boat on the Nile, lone manor, etc.), but happens in the middle of a city, you could end up with way too many locations and people to handle. So the trick is to *not* first place all the clues, and then hope that the players find them. Instead just make a list of the clues as bits of information, and be flexible where those bits of information can be found. If the players have an idea to search a place or talk to somebody, and the idea is somewhat reasonable, just decide that the clue is there. That might feel a bit like cheating, but it ends up having a flow that corresponds to expectations: The TV detective doesn't lose endless time by searching the wrong places and talking to the wrong people either.

My final advice is in disagreement with the Sly Flourish article: Yes, "players want to feel like their decisions matter and their actions lead somewhere". But that doesn't mean that the game world and the villain NPC have to be passive and sit and wait for the players to work through all the clues. Instead the villain NPCs have to be handled like characters with their own motivation, goals, and means. The villain should react to the investigation of the players. Again that conforms to expectations, detective stories frequently have the murderer kill another victim because the detective came close to getting a vital clue from that person. Because this is D&D and not Agatha Christie, the villain NPC might have far more possibilities in a D&D adventure, up to and including attacks on the players.

I have this concept in mind of the "turn-based" approach to role-playing. Basically the risk in D&D sessions that are heavy on role-playing and light on combat is that certain players take the lead and go off on long solo performances, while the other players fall asleep and the story isn't moving forward. Thus I try to gently nudge the role-playing into a structure where I give turns to other players, and to NPCs. Thus if one player goes on endlessly negotiating with a merchant, I say to the next player "Okay, so while Bob's character is negotiating with the merchant, what do you do?". And once I've given every player the chance to act, I think what a reasonable response or action from the NPCs, especially the villain, would be. That concept is explained beautifully in the recent WotC adventures Murder in Baldur's Gate and Legacy of the Crystal Shard. The main advantage is that it kind of puts the adventure on a clock: The game world is alive and stuff happens, even if the players dawdle. Once the players realize that, it creates better drama, because they KNOW that they don't endless time to find the solution.

So the next adventure will be an experiment on how successfully me and my players can handle an investigative adventure in a city. If that doesn't work at all, I will have to rethink my idea for my next campaign, because the adventure path I have chosen has a lot of investigative parts as well. Dungeon crawls are comparatively easy, but I hope that we can do more than that.