Creating a Mystery Adventure

A raven in a suit next to a dead songbird with a lute.

Creating a Mystery Adventure

Mystery adventures are great for any level and variety of character types because they use the players’ brains more than the characters’ powers and statistics. However, they take considerably more planning and preparation than your standard shoot-’em-up adventure.

I’ll give an example from a rather complex PBEM mystery set in my house campaign island of Saldon that I have just finished running for a low-powered Dungeons and Dragons group.


The first thing I had to do was deal with the question of magic, which can really make mystery investigation far too easy. I required the player characters to be low level, to prevent them from having too much magic to throw around. But that wasn’t sufficient, because the setting was going to be in a city. The characters could, possibly, hire magical help … or get the city guards to comandeer magical help. To get around this, I determined that there were only two significantly leveled mages on the island, the court mage and a powerful and mysterious figure called The Necromancer. The former was called in early but was otherwise kept apart from the group by her social class, levels of bureaucracy, and magical research into red herrings thrown into her path. In other words — I used her as a source of information when it was useful and kept her out of the way all other times. As for The Necromancer, I had him simply vanish — either deep in research and not answering the tower door, or teleported away, perhaps to sunnier and warmer climes for a tan and some surfing. The player characters never knew, and frankly, it didn’t matter.

All other mages on the island were too low-level to be able to muster the kind of spellpower that could offset my mystery.

Other games that deal with magic or extrasensory powers must come up with similar methods, which might include running the adventure in a place that renders magic or psychic powers null, or making the culprit have superior magic or psychic powers to deflect supernatural or extrasensory questioning without raising undue suspicion.


So, with that out of the way, I could settle down to creating the mystery adventure. Of course, I didn’t quite follow these steps so neatly — I had a spiral notebook filled with scribbled notes. But I hope that these steps will help you organize your thoughts better than I did at the time. They follow the good, old-fashioned journalistic set of questions: What, Who, Why, How, Where, When, and So What?

Step One: What?

The first step is to decide what kind of crime you want to base the adventure around. Mysteries come in several flavors, which can be mixed and matched according to the GM’s desire. Here are some of the most basic categories and examples:

  • Crimes against the body:
    • Murder
    • Assault
    • Kidnapping
    • Threats
  • Crimes against property:
    • Theft
    • Vandalism
  • Crimes against reputation:
    • Blackmail
    • Forgery
    • Framing
    • Impersonation
  • Crimes against peace of mind:
    • Mysterious Occurences

What: Murder. A good, old-fashioned mystery. Along the way, however, I got to throw in some mysterious occurences, vandalism, impersonation, forgery, and more.

Step Two: Who?

Now you have to figure out what it is that the players are going to be TRYING to figure out throughout the game. Who? What? Why? Alas, this isn’t always as straightforward as you’d think.

  • Who (Mark 1): Who is the murderer? I decided that a demon is a good fantasy standby — a creature that will stop at nothing and that can be killed with few feelings of remorse on the characters’ parts. However, that led me to another who.
  • Who (Mark 2): Who summoned the demon? A secretive black magician, I decided.
  • Who (Mark 3): Who was killed? A bunch of young nobles, I decided, including some relatives and friends of the player characters. That would give the PCs a reason to investigate and pursue the case through thick and thin. Revenge is a wonderful motive. Plus, it would give the murder the political edge that I wanted it to have.

Step Three: Why?

Every criminal has a motive. Figuring out that motive can be a key to solving the crime. A few standard motives include power, money, jealousy, revenge, and sex.

Why: Power. I wanted this to be a very political mystery. The black magician was also a political meddler who wanted to use the demon’s power to propel himself to the city throne, currently being held by an elderly regent who had announced that he’d name a king within a month or so.

Step Four: How?

Next comes the modus operandi. How did it get done? In some mysteries, this is the focal point. I didn’t feel like dealing with the intricacies of forensic investigation in my game, however, so I made it pretty straightforward.

How: The demon burns the nobles into charred chunks. Hmm. Now this lead me back to How again, because the demon should, classically, be confined to a summoning circle that would protect the summoners from its powers. Clearly the circle had to be broken. In deciding how that circle got broken, I was able to set up Red Herring 1—which I’ll describe later.

Step 5: Where?

There are several Wheres that must be answered.

  • Where (Mark 1): The adventure setting. I set the adventure on a remote island locked away from all air or water traffic by winter storms. This let me keep my cast of suspects down, create a sort of “locked-room” mystery (the murderer must still be on the island — there’s no way off until spring!), and use weather for dramatic effect (the constant winter rainstorms kept the characters miserable as they investigated).
  • Where (Mark 2): The murder setting. A ballroom, I decided — that would be large enough for a bunch of spoiled noble kids dabbling in black magic to carry out their ritual. And to get those characters involved quickly, a ballroom in the house right next door to the one where the characters were all gathered.

Step 6: When?

When the event occurs can be very important. I wanted maximum effect with minimum potential interference from NPCs.

When: Around midnight. That made sense black-magic-ritual-wise and allowed me to wake the characters up in the middle of the night with shouts for help and the unsteady glow of a house on fire. It also meant I could delay bringing the city guards in long enough for the PCs to get to the scene first and do some preliminary looking around.

Step 7: So What?

This means, why should the PCs care? What gets them involved? What’s the hook?

So What?: First, several of the young nobles killed were friends or relatives of the player characters — two brothers, a next-door neighbor. Second, I made it clear through NPCs that a political motive was suspected and that this “arsonist” could be a threat to other nobles (like the PCs) who might be eligible for the throne. Third, I had the NPC at whose house the PCs were staying emotionally request their help in investigating the shocking murder. Since they were his guests, they had some obligation to agree to help him. And since he was in his 50s, he wasn’t expected to go out in the storms himself to investigate!


Now that you have the core mystery, it’s time to think of ways to complicate and obscure it. Why? So that the PCs don’t solve it too quickly, of course. A good mystery should have them tearing out their hair as they struggle to pull all the threads together into a coherent story.

Step 8: Assign PC Dark Secrets

This is an optional step. It makes the game much darker and grittier, and the players much more paranoid. Dark secrets create a hardboiled feel, in which nobody, including the heroes, is truly clean. Personally, I enjoyed running a game in which the PCs were dirty and trying to cover up, and the players enjoyed it, too. But some groups aren’t going to. Players with strong moral codes may object to playing a dirty character, and some players will, for personal history reasons, object to some of these dark secrets while agreeing to others. Use this tactic carefully and sensitively, and use good taste while planning the game.

In this step, you work secretly with each player to give the character some dark secret. The player wants to keep this secret hidden, but the GM should stack the deck so that the dark secret will need to be revealed (unless the player is an adept and creative liar). My list of potential dark secrets included:

  • drug addict
  • alcoholic
  • secret, scandalous marriage
  • drug runner
  • murderer
  • prostitute
  • illegitimate child
  • worked for criminal ring
  • government spy
  • adultery
  • incest
  • secret identity
  • parents are criminals
  • unacknowledged bastard of someone important
  • famous due to plagiarism of another
  • assassin
  • thief who carried off a big heist
  • involved in black magic
  • character is a magical creation
  • dark cult activities
  • character is a vampire’s blood thrall
  • dying of disease
  • cursed
  • sold out friends
  • blackmailer
  • pedophile/rapist
  • embezzler

I didn’t use all of these, and one or two players refused to have a dark secret of any importance. Others created characters who were as bad, if not worse, than the demonic villain!

Note that, as much as possible, I tried to tie the dark secrets together. For example:

  • PC Taheton was the father of much younger PC Petrucio. Taheton’s player knew this; Petrucio’s character did not.
  • Petrucio was in a scandalous marriage with a bastard child. Or so he thought. But actually PC Oran was the child’s real father.
  • PC Cecilio’s evil familiar drank the life force of the elderly, including Taheton’s aunt. That life-draining was one of Cecilio’s dark secrets. But Taheton didn’t know what was going on. When the dark secret came out … then Taheton realized his aunt, who had been fading quickly, was one of Cecilio’s victims.
  • PC Cecilio and PC Jarret’s father was killed by a group in which PC Taheton had been a member when much younger.
  • PC Albertus had been travelling with PC Cecilio and PC Jarret’s father when PC Taheton’s adventuring group attacked it and killed the father. PC Albertus ran away when the attack began, making him think of himself as a coward who betrayed his friends’ trust — one of his own dark secrets.
  • And so on…..

Next, write a secret note to each PC that tells them a little about the other PCs. Use this to cast suspicion and to reveal clues that, if every PC put all their notes together, would reveal the truth about the various dark secrets involved. Feel free to spread false rumors, too — this is another way to develop red herrings for the PCs (see below).

When the PCs slowly learn that they can’t trust each other, investigating the actual crime becomes that much trickier!

Step 9: Assign NPC Dark Secrets

Now do the same thing with several important NPCs. Again, I tried to link these dark secrets to the PCs when I could, but sometimes I didn’t because I had plans for the plot. Thus, for example:

  • NPC Amescua was the host to all of the PCs when the murder occured. He was also, unknown to others, the secret brother of the Guildmaster of Assassins on the island. And both were the hidden-away sons of the old murdered king — thus the rightful heirs to the throne.
  • NPC “Unnamed Servant” was the victim whose sacrifice was supposed to summon the demon. However, Unnamed Servant was the valued servant of a vampire who lived on the island. The vampire broke into the ballroom to rescue his endangered thrall, breaking the circle. This is what let the demon free to kill all the nobles.

Step 10: Develop Other Subplots and Motives

Now sit down and think about other subplots that may help you flesh out the adventure and the campaign setting. Consider also the motives of NPCs other than the villain, especially to ensure that the mystery proceeds logically.

Subplot 1: A wanted political rebel is planning his escape from the island through magical means. The rebel was the secret friend of one of the PCs (a dark secret) and if discovered, the other PCs would have to decide whether or not to let him escape. (As it happened, he wasn’t involved, and the PC helped him escape during the post-game wrap-up).

Subplot 2: NPC Amescua, rightful heir to the throne, doesn’t want to make himself a target by claiming it too early. He is sitting back and waiting. When the time is right, he’ll make his move. This is part subplot, part motive — the subplot is that he can be discovered as being the rightful heir, the motive is a means of keeping him in the background but helping the PCs when they need it. (In fact the regent eventually figured out his identity and declared him the king at the end of the game during the wrap-up sessions. I was going to have Amescua reveal his identity if needed to keep the players investigating, but it wasn’t needed.)

Subplot 3: NPC Amescua admires the much younger PC Morgana, daughter of a friend of his. Their ages are much different, especially since he’s in his 50s and she’s a very young woman of elven descent. (He asked her to marry him at the end of the game; she agreed, even though she’d been flirting with a half-drow PC. Her theory: she’ll make him happy until he dies, and then she can marry the half-drow.)

Subplot 4: Somebody in the Assassin’s Guild is trying to kill the Guildmaster and take over. He tried to use the PC Jarret, who was an assassin (a dark secret) by sending fake messages from the Guildmaster to kill Lord Amescua, whom he knows the Guildmaster is, for some reason, protecting. (Jarret questioned the order and brought the fake note to the Guildmaster, who promptly began an internal investigation. In the post-game wrap-up, the traitor was killed and Jarret promoted to his position in the guild.)

Subplot 5: A local crimelord, “Fat Boy Clarke,” is owed money by PC Morgana’s brother, who died in the ballroom fire (thus motivating her). He sends his lackeys out to try to get the money from her. (She never met with him face-to-face during the PBEM, and in the end, with her marrying the newly declared king of Saldon, the crimelord decided to cut his losses and hide out for a while.)

Along with these subplots and others, I also developed motives for NPC actions that would help me move the plot to where I wanted it to go.

Motive 1: The demon’s motives after being freed. In my murder plot, I freed the demon so he could murder the nobles. But what then? All of the sudden I had a demon loose on my island. Now I began to develop a subplot based around the demon’s motive that was even more threatening to the island and PCs than the original murder.

I decided that the demon’s motive would be to take over the island. Why? To cause misery. The demon feeds on misery and human anguish, I decided. Uh-oh. Now I’m back to creating a subplot using the same rules as needed for creating the core mystery plot. So I have a who and a why. Now, how? By possessing the regent and passing laws and regulations that would increase misery on the island. Of course, the man who summoned the demon knows about the demon being free. so all of the sudden I had to consider his motive, too.

Motive 2: The summoner is hiding out, afraid that the demon might kill him and searching for a way to regain control over the demon again. This explains why he won’t go to the guards immediately, confess what he’s done, beg for protection, and end the game through NPC actions.

Motive 3: I also needed a reason for the guards to carry out what will be rather restrictive, violent orders from the possessed regent. I decided this was because the Guard Captain Abano is grimly obssessed with law and order and determined to protect the regent at all costs. Of course, he doesn’t know the regent is possessed, so he sees the raids, the questioning, the arrests on suspicion, and the curfew as methods of hunting down the “arsonist” before the “arsonist” can kill the regent.

Motive 4: There are two other people out there who knows about the demon — the vampire and his rescued thrall. So why don’t they tell the guards? First, because the vampire lives a life incognito, writing political pamphlets, publishing a seditious political newspaper (another subplot and source of several dark secrets — as well as a fun way for me to infuriate the PCs with gossip and insults), and generally avoiding adventurers with stakes. He keeps his thrall quiet for the same reasons. Second, because the vampire doesn’t really care. The social chaos helps him hide his own morally shady feeding methods, and he figures the demon isn’t a direct threat to him.
And so on….

Step 11: Red Herrings

As if the adventure weren’t complicated enough, now it’s time to develop the red herrings. These are the false clues and wrong paths that the PCs may investigate, drawing them away from the real investigation.

Red Herring 1: The broken ballroom window. The vampire is a logical suspect in the arson, so I pointed the PCs in his direction using clues such as the broken window, footsteps, signs of a person with inhuman strength and signs of a person who scaled a sheer cliff to leave the estate.

Red Herring 2: A threat against the regent. The demon set up a fake assassination attempt against the regent by possessing a servant from the burning estate, attacking the regent, and then jumping from servant to regent. The possessed regent then killed the “assassin” and used the “attempt on his life” to rationalize the passage of the restrictive and oppressive laws. The demon also staged an arson attempt on the palace to draw attention away from the regent as a suspect.

Red Herring 3: I tried to cast suspicion on the wanted rebel who figured into one of the subplots, but this herring was never really picked up.

Red Herring 4+: The PCs’ dark secrets themselves confused the trail quite a bit. There were plenty of PC-originated murders, betrayals, double-dealing, secret searches, and other entertaining mischief to keep me entertained and the PCs busy and, often, distracted.

Step 12: Organizing the Mess

As you can see, developing a complex mystery can be as hard for the GM to keep track of as it is for the PCs.

Keep a notebook with the general plot and NPC secrets and motives written down, and include pages about each character’s dark secrets and what each character knows about the other.

Ask each PC for a list of what he or she is carrying or owns, in case the PCs search each others’ belongings or rooms. Make sure to ask the PCs to give you information about the incriminating evidence each has, too. My PCs were very creative in telling me what books they owned, titles of pamphlets they carried with them, codes they used, and so forth.

Keep a general flowchart of how you see the plot progressing, with a timeline of scheduled events. This chart is going to change due to PC actions, but at least it gives you a place to start, and prevents you from forgetting a vital clue you’d intended to reveal.
If you have a variety of clues, keep these in labeled envelopes so that you can find them quickly. A folder with pocket dividers can be useful for keeping them organized, as can hole-punching the envelopes and putting them into a three-ring binder.

Step 13: Providing Clues

If you’re using visuals, provide maps of the crime scene and major locales (suspects’ houses, for example).

If you’re using visuals, write out text-based clues. Use different fonts for different people, and use them consistently … so that as soon as the PCs figure out that a certain font is a certain NPC’s “handwriting,” they can then pull out all of the clues using that font and know that all originated from the same NPC. Similar but not exactly the same fonts can be used if you’re trying to set up a forgery situation — give the players a chance to notice the differences and figure out that some of the notes are fakes. Paper color and type can be a clue, too, if you’re really feeling creative — for example, a noble might always write on heavy stock paper, but a forgery might be written on a lighter-weight, lower-quality paper.

If you’re gaming face-to-face (or in print), develop patterns of speech or behavior that may provide clues to, for example, an impersonation (like the possessed regent) or general untrustworthiness (such as shifting gaze, wiping “sweaty” palms on one’s pants legs, etc.).

Go ahead and drop clues to the PCs’ dark secrets whenever it’s logical. For example, a PC who goes out at night on a secret mission might have damp shoes that morning at breakfast, or have suddenly come down with a cold from the storm. A PC who is alcoholic or a drug addict will have certain physiological signs that attentive characters might notice.

(Note that I tried to remind the PCs when they were feeling in need of a “fix” in order to force them to roleplay the dependence better.) A PC having an affair may return smelling of perfume or cologne, or have socks on inside-out. These are the sorts of details that will drive the players crazy, to some extent — they don’t want their dark secrets revealed — but as long as the clues are dealt out evenly, there’s nothing the PCs can do about it but lie as quickly and adeptly as possible. (And face it, most players enjoy being put on the spot and given a chance to roleplay a dramatic scene!).

Step 14: Gathering the Players

“Oh no, it’s a mystery,” my core face-to-face group often groans. “We’re no good at mysteries.” Choosing the right players for a mystery is very important.

Hack’n’slashers don’t like mysteries. Too much thinking and talking, not nearly enough action. Good players for a mystery game are excellent roleplayers with a range of real-world knowledge, lots of patience and a good sense of humor.

Roleplaying is important, because much of the fun of mysteries is in interrogation, lying, deception, bluff, trickery, and creativity.

A range of real-world knowledge can help the GM figure out what kinds of clues to drop. Got a player who’s good at puzzles? Put one in. Got a player who reads a lot about etiquette? Use it as a clue (e.g., the so-called “noble” who chooses the wrong wine to go with the fish, or picks up the wrong fork, or uses the wrong title….). Got a player who knows something about forensic anthropology (say, a fan of the TV show CSI)? Make sure that corpse reveals something significant about how the crime was committed. In other words, play up to your players’ strengths. Players who don’t know much about anything just aren’t very good investigators.

Lots of patience is important because mysteries are slow. A sense of humor is also important because mysteries are slow … and red herrings can be frustrating. The ability to laugh at one’s own errors is indispensible.

Remember: be flexible as you respond to player insights, be fair, have a way figured out to leak more clues if the players are dead-ended, and have fun.

Originally written February 2, 2001

Image Source: Illustration from The Fables of Florian, 1888.

I read, write, roleplay, travel, teach, and occasionally do research. I am a lizard, a warrior, a minimalist, and a scholar.
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