A fog shrouded dock at 3 am. The silence is shattered by the peals of the watchman’s bell. He screams for a chirurgeon-- but he knows that the body at his feet is long dead. The careful stitching on her back indicates the handiwork of the mysterious killer. Just like the last body, just like all the ones before. Tomorrow, come daylight, the city will riot. After all, the king had promised that the man swinging from the town gate was the killer!
How to Host a Murder Mystery in your RPGs
Do you need a break from storming castles, plundering caverns, meddling in the affairs of gods and kings, and saving the world? You should consider running a murder mystery campaign, or taking a break from your regular story to throw your adventuring party a thematic curve ball.
Murder mysteries are tense, exciting, sometimes scary, and most importantly fun. Here are 5 beginner friendly tips for navigating a good murder mystery story line in your RPG, regardless of which system you prefer.
Your players are intimidated, but you don’t need to be
Your simple mystery seems way, way more complex to the players than it does to you. After all, you’ve already “read the last page” of this book. All the clues you drop feel like they have neon lights and klaxons on them, but trust me, unless your group has done several murder mysteries with you, they are going to feel overwhelmed if you put any effort at all into prepping your mystery.
In my most recent campaign we had 4 players, a homicide detective, a counter terrorist agent, a government grey-hat “problem solver,” and a doctor/forensics expert. We played about 40 sessions total over the course of the mystery, and one of my goals was to ensure that the identity of the killer didn’t seem to come out of nowhere. So I took what felt like a huge gamble at the time and introduced the killer in session three.
The killer was another government “problem solver” although more senior than the PC. He sought them out, introduced himself and then led them to the scene of his most recent victim. Of course, he had a cover story, but I was very worried that they would pinpoint his guilt earlier than I had planned for. Instead, they treated him as an ally and didn’t begin to suspect him for about another 20 sessions!
Your players think the killer can be anybody, and have no idea if they’ve met this person or not, but you know exactly who it is. That leads us to our next tip:
Figure out what player expectations are, and meet them
Are your players willing to fail to find the killer? If so it’s okay to pre-define who the killer is, and if the players can’t figure it out, they can’t figure it out. However, most groups won’t find this satisfying. Like with a good movie, your players are probably expecting a climactic final confrontation with the killer. Two good ways to facilitate that are to have a “quantum villain” and introduce a game mechanic for progressing the investigation.
A “quantum villain” is a villain that begins as a sketch of a character and becomes more concrete as the story progresses. No matter how you run your campaign there will be times when your players latch on to a red herring, a detail that you never meant for them to follow, or come up with a pet theory that has nothing to do with your killer. After all, unless you’re playing with professional criminal psychologists, profilers and detectives, they don’t actually know how to investigate these killings. Instead their actions are going to be largely influenced by popular media, the social dynamics of the group, and the descriptions you provide. So, you can use that! Follow the fun. If your party has a pet theory they love, or if they are really enjoying following up on a “lead” that had nothing to do with the lead you prepared, incorporate it. Let them influence the mystery. By about halfway through the campaign they may have finished designing the killer for you-- and you should give your audience what they want!
In my campaign, the killer was called “The Stitcher” based on his habit of sowing his victims together or to animals and things in part of his twisted violent psychopathy. The victims, before they had been ID’d, often got a placeholder name based on how they were configured. A man and woman sewn together at the hands became “the couple” and a man staged on his hands and knees with rats sewn to his back became “the altar.” One player speculated that the killer was recreating the Tarot cards of this setting. He wasn’t-- until my player had that idea. That night I created a custom tarot deck, retroactively incorporating previous victims into the symbolism-- and boom, now my Stitcher was an amateur chaos magician as well as a nutjob.
Of course, sometimes even a quantum villain can’t become what the players want. Unfortunately, in my campaign some offhand remarks and jokes that got taken too seriously led 3 of the players to suspect that I had collaborated with a fourth player to make the killer a member of the party. (That would have been super cool and creepy but it had genuinely never occurred to me!) Well, that player had absolutely no interest in being the killer, and even if she had, we hadn’t set it up to work that way in the first place. Game mechanisms to the rescue!
I created a system of leads and clues. A lead was a red index card with a statement on it like, “there is something very different about this particular victim” or “this diplomat is clearly hiding something.” Players could progress leads by making skill checks, going to key places, or taking other player driven actions that related to that idea. Progressing a lead would add another line to the card, like, “this victim was killed by a mugger--why did the serial killer claim credit for it?” They would also be rewarded mechanically. Depending on the game system, you might give them gold, advantage, or in my case my players could increase a custom knowledge skill called “Profiling”, which they could use on certain checks in place of their weaker knowledge skills.
After progressing a lead a few times it would become a clue. The red card was retired and it was replaced by a green card that contained a fact. For the rest of the game the players could confidently know that if new information came up that contradicted one of their facts it could be disregarded. At one point my party skirmished with the killer in a dark sewer. The killer escaped without being identified-- but they did clearly notice that he was unusually tall, at least 6’2”. From then on they had a fact: the killer is tall. That eliminated several red herrings for them, saving them valuable time following up on suspects that were dead ends!
If your setting has magic, figure out how to deal with it before session 1
If your setting has sufficient magic that would make forensic investigation trivial, you need a way to keep the investigation fun and protect it from a deus ex magician. If your players can interview the deceased by Speaking With Dead, you need to already have a plausible answer as to why the deceased never seems to know who killed them. Generally speaking, this means your killer will need to have access to magical abilities that will counter magical abilities your players have in their bag of tricks. Make sure you have a clear idea of what magical abilities your players have, and which ones they are likely to pick up during the campaign and make sure there aren’t any silver bullet spells that will crash all your carefully laid story pieces into a brick wall.
However, don’t leave the mage(s) feeling utterly useless. Maybe the dead can’t identify the killer, not because he’s captured all their souls and Speak with Dead never works, but maybe they simply have no idea who it is! Your mage might then think to partner with someone with great artistic talent so they can work together on making a portrait of the criminal to help with identification!
Another major potential pitfall is tracking spells. Be ready to have plausible decoys or other ways of preventing the party from simply homing to the killer on the second session-- but don’t make tracking entirely useless. A tracking spell that finds an abandoned lair can still result in a treasure trove of info about the killer, without putting the party right at his doorstep.
Learn your systems social combat systems and use them a lot
In forty sessions we had 3 major combat encounters. The final battle with the killer, a skirmish with the killer, and a battle with some ruffians that was not planned and was the result of some very stubborn players. Instead of combat encounters, we had lots and lots of social combat. My system happened to have really exciting rules for social combat, but if your system has lackluster mechanisms feel free to add in some house rules and go over them with your players. In a murder investigation you are going to be interviewing and interrogating lots of witnesses, victims, angry activists, furious police chiefs, union bosses, shady merchants, ruthless political leaders, and quite possibly the killer!
Social combat should have a clear objective for both parties, the players generally want true information, and the suspect/witness wants to not go to jail or become a target for the killer. In other cases, like dealing with supervisors and leaders, the party wants to justify their work, and the supervisor wants better results than the party is currently getting. Have a clear win or lose condition and reward the party with additional benefits if they win. Generating leads and clues is a great one. Securing additional funding for equipment, staff and weapons is another. Losing an encounter should generate false information (I recommend not ever creating false lead cards-- don’t mess with the sanctity of the lead and clue system!) or having your boss assign an NPC to look over your shoulder.
This will make up most of the combat in your game, so win or lose, give the players experience from these encounters to keep them leveling up.
Have at least one lead or clue ready for every play session
Every play session should have at least 1 NPC or location who can generate a clue. Don’t guarantee players earn it, but make sure the chance is always available. For example, every victim’s crime scene should have a lead. The killer was there, for sure, and some of the best information they can get will come from these crime scenes! But don’t give them a lead for free. If they show up and ask all the wrong questions, and flub every dice roll, you can tell them that they are missing something and can try and earn the lead from this scene again later.
In the next session there should be a new opportunity for a new lead, plus they can analyze last session’s evidence in their lab and have another shot at scoring that lead. Alternatively, you can have a new witness contact them to get them back on track as far as what they missed at that scene.
You should also be prepared to quash a player theory about a location outright. For example, I described a particular dance club in more detail than usual. I was just trying to bring some color to the world and was riffing when I was setting the scene, and the player’s applied Checkov’s Gun theory to that unusual level of detail. I eventually killed the theory outright because I didn’t have anything to feed them that would make sense for what I had planned next, so I told them, “Your police instincts are tingling here all right, and people are lying to you-- but you realize it’s because this is a hotspot for opium dealers, not because anyone is hiding that they saw The Stitcher here.” Don’t be afraid to let your players who are not homicide detectives get free information from their professional characters. They don’t need to roll for everything!
Conclusion
A murder mystery can be a great side quest, one shot or a whole campaign. If you incorporate these tips, trust yourself to come up with a couple good twists and turns, I guarantee you and your players will have a blast. After all, what’s more fun than a trail of bodies, a foggy city, and the nagging sensation that you’re next?
