I was running an adventure this weekend from a module that I had downloaded from the net. Central to the plotline was a mystery, a political situation in a small town, stories of an ancient Curse, all calculated to drive the PCs to an above-ground dungeon which could also be called a Mansion.

While the content that was provided was excellent, the author had ignored a couple of plot holes – or plot opportunities – as large as the mansion that was the central feature. Specifically, a historical mention of a drought and a plague of snakes, and the arrival virtually simultaneously with those events of a band of Druids who had set up shop in a grove outside of town. To anyone except the author of the module, it would seem obvious that these events are possibly linked, and that investigating the Druids was a rational step in solving the mystery.

The problem was that no details useful in roleplaying the Druids had been supplied. There was no statement as to what information they could contribute if their cooperation was won over, no suggestion as to what fees & services they might demand in exchange for their assistance – in fact, beyond the fact of their existence, and that they had converted one-quarter of the locals to their theology, there was virtually nothing about them.

Since I had already been preparing to write an article on how to do Mysteries in RPGs, the failures of this adventure in this department struck home all the more forcefully. So, what should the author have done? I’ll get to that a little later. Let’s start by looking at the taxonomy of mysteries and laying some groundwork…

The Elements Of A Mystery

Anytime you have a question that needs answering in an RPG, you have a mystery on your hands. It might be a small-scale puzzle whose solution only requires asking the right person the right question, or it might be quagmire of lies and deception that will require substantial investigation.

The Focus

Mysteries all start with a Focus. In a crime-style mystery, this is the victim; in other kinds of mysteries, it may be some unexpected scientific outcome or unexpected event or surprising decision or action. In other words, it’s always “X did something” or “Something happened to X”, and the question to be answered is always, “Why?”.

From the circumstances and conditions, clues are gathered and a list of potential suspects – theories – is formed. These are then investigated, hopefully leading to other clues, eliminating suspects until only one remains, and all clues have been tied to this person or cause with none remaining to be investigated.

cell1 topleft 'who' cell2 topright 'why' cell3 bottom 'how when where'

The Suspect Triangle

At it’s heart, a mystery – any mystery – can be summed up, “Who did what, why, how, when, and where?”. These elements are summed up in the Suspect Triangle. The top half of this inverted triangle covers Motive, subdivided into Who and Why, while the bottom half deals with Means & Opportunity in the shape of the questions How, When, and Where.

All three areas of the triangle need to be filled with something that is uncontradicted and undisputed before you can consider someone a genuine suspect, and only if you have eliminated all other suspect triangles can guilt be confirmed and the mystery be considered solved.

Of course, that’s a very crime-oriented approach; but substituting “What” for “Who” covers all the other types of mystery which may be encountered.

The Clue Process

Each clue is subject to a three-step process, without fail.

  • Detection, in which the presence of a possible clue is identified;
  • Analysis, in which the specifics of the clue are determined; and
  • Interpretation, in which the meaning and significance of the clue with respect to one or more suspect triangles is determined.

Each clue adds an item to one or more of the areas of the suspect triangle for some suspects, while demonstrating that one or more other suspects could not be responsible.

The Investigation Procedure

This relationship between clue and suspect triangle is depicted in the graphic showing The Ideal Situation. Ask the right questions – and each question-and-answer constitutes a single clue – and you will only be left with a single suspect, the guilty party.
one truthful clue eliminates several suspects

when all innocents are eliminated, only the guilty remains

This question-answer-meaning trio corresponds with the structure of a clue. The trio can be taken literally, where each question is asked of a witness to the event being investigated or to part of the circumstances surrounding it, or metaphorically, where the question can relate to physical evidence, historical relationships, financial information, and so on.

The Lie

Mysteries would be easy to solve if everyone told the truth, the whole truth, and nothing but the truth. They don’t.

One person in particular – the guilty party – has every reason in the world to lie. This is so axiomatic that discovery of a lie is tantamount to elevating the liar to the status of Prime Suspect.

A lie works as depicted in the illustration: by shifting apparent guilt or by contradicting part of the suspect triangle to show that the guilty party could not have committed the crime. In this case, a truthful statement would have led directly to the first suspect (the one on the left), but the lie makes it seem like the second suspect is guilty rather than the first, or makes it appear that the guilty party could not have been responsible because he no longer had one or more of means, motive, or opportunity.

Mysteries in Media & Fiction

Making a mystery more interesting requires that things not be so clear-cut. One of the easiest ways of achieving this is the introduction of a lie for some reason other than guilt in relation to the main mystery. Blackmail, an adulterous relationship, the commission of a minor but unrelated crime or impropriety, seeking to protect someone who the liar thought was guilty, protection of social status or reputation; there are a multitude of possible reasons for such a deception. Only once this second lie has been identified and the deception penetrated can the other lie, that of the guilty party, be verified and proof of guilt obtained.

This gives us the simplest of satisfying mystery structures – the Linear Mystery. The name derives from the fact that one step follows another in logical progression, like the pages of a script or the chapters of a novel. The first clue describes the circumstances of the crime; the second represents the line of questioning that initially leads to the questioning of the guilty party. The Guilty party lies, of course. The next clue represents the questioning of everyone else except the second liar. Everything else not shown in the linear mystery is essentially irrelevant, window dressing and red herrings.

Going too far

It’s tempting to set up a mystery in which every person interviewed has a reason for deception as a way of increasing the difficulty of the puzzle. Having tried this for myself, I can state that it is definitely going too far, and ended up generating more confusion once the lies were detected than is really suitable. There are better approaches, which I will discuss in due course.

The Clever Alternative

At this point, I have to confess to a fondness for the Columbo telemovies, especially the later ones. Many of them use intelligence and cunning in place of such crude tactics as described by the linear plot. Arranging matters so that everyone can speak the truth and still be misleading is a far better solution than a linear plot. This requires a deception as to the nature of one of the lower elements of the suspect triangle – altering the apparent time of commission of the crime being investigated, for example, or the apparent whereabouts of the prime suspect at the time of commission through the use of some form of impersonation. Having everything but one small overlooked detail covered shifts the nature of the mystery to a battle of wits between the guilty party and the investigator.

Further Complications

Investigators generally have one or more additional complications to work around. These usually (but not always) take the form of legal requirements which must be met before certain clues can be accessed.

The Parallel Plot

Roleplaying Games do not proceed in a nice, neat, Linear fashion. Players are too creative, and too cynical, for any such simple structure to suffice. They are too prone to reason, “If I assume that {suspect 1] is guilty, how can I reconcile that with the evidence the GM has put before me?” They will then test the assumptions they have made, setting traps, violating strict legal practice regarding the obtaining of evidence, or doing whatever else is necessary.

The solution is the Parallel Plot. I simply take a Linear Mystery and list of possible suspects and use the player’s own techniques against them. I shortlist a group of suspects, and then determine which ‘clues’ are lies and deceptions of various types, the penetration of which will lead to the unmasking of the culprit. I then do the same for the second suspect in the shortlisted group, and then a third.

This prevents shortcutting the mystery by ensuring that the Nth approach to the puzzle is the correct one. All the lines of enquiry the Players make which precedes the Nth approach lead to dead-ends, because the correct line of enquiry is always the last one.


This might seem like a lot of work, but it can be achieved relatively simply if the GM, when designing the adventure, employs only a short phrase to synopsise each clue. Setting up a table like this:

column1 clue source, column2 clue summary, column3 true/false for suspect1, guilty column4 true/false for suspect 2, and so on.

makes it simple work. For each clue, you simply need to determine whether the clue is true or not, given the identity of the guilty party (shown across the top). Using this table, you can quickly identify which statements need to be prepared in more than one form (truth or lie); for each lie, you can add a notation about why the source of the clue is lying, how the lie can be penetrated, and so on. Numbering each clue in this respect and indexing by source down the left-hand column, again as shown, turns the table into a crib sheet showing all possible solutions.

The result is that you have a list of the clues (which don’t change, but whose circumstances might), and additional notes regarding them, all of which can be organised by source and by clue number. Any clues that don’t specifically lead to the guilty party are, by definition, clues pointing to a non-guilty party – a red herring or a dead-end.

Beyond The Clichés

You can wrap a mystery, created in this manner, around any genre you like, from Fantasy to Pulp to Superhero to Western to Cthulhu to Sci-Fi, because the structure doesn’t change, only the content.

Each of these genres will have its own clichés in this respect. I urge you to get these all out of your system at once so that you can concentrate on more interesting and original approaches thereafter. By way of example, the first adventure that I ran utilizing the Parallel Plot structure was for the graduation exams in my trainee superhero campaign, where each player was presented with the same mystery in turn, and had to solve it. All but one of the five student PCs chose a different guilty party because the right answers kept changing to whatever was most interesting to play. The setting was a convention of butlers – one of whom was the killer and one the victim. I was even able to title the ‘adventure’, “The Butler Did It!” without giving anything away – this article has been titled in reminiscence of that adventure.

Technology & Magic

In the foreword to Asimov’s Mysteries, Isaac discusses the perceived difficulties of uniting the mystery genre with science fiction in his foreword. I’d like to start this section by quoting some selected passages from that essay:

…yet science fiction writers seemed to be inhibited in the face of the science fiction mystery.

Back in the late 1940s, this was finally explained to me. I was told that ‘by its very nature’ science fiction would not play fair with the reader. In a science fiction story, the detective could say, ‘But as you know, Watson, ever since 2175, when all Spaniards learned to speak French, Spanish has been a dead language. How came Juan Lopez, then, to speak those significant words in Spanish?

Or else, he could have his detective whip out an odd device and say, ‘As you know, Watson, my pocket-franistran is perfectly capable of detecting the hidden jewel in a trice.’

Such arguements did not impress me. It seemed to me that ordinary mystery writers (non-science-fiction variety) could be just as unfair to the readers. They could hide a necessary clue. They could introduce an additional character from nowhere. They could …

…The point was, though, that they didn’t do anything. They stuck to the rule of being fair to the reader. Clues might be obscured, but not omitted… …The reader was remorselessly misdirected, misled, and mystified, but he was not cheated.

It seemed, then, a matter to be taken obviously for granted that the same would apply to a science-fiction mystery. You don’t spring new devices on the reader and solve the mystery with them. You don’t take advantage of future history to introduce ad hoc phenomena. In fact, you carefully explain all facets of the future background well in advance…

Magic and the other trappings of Fantasy are just as problematic, because (by definition) they contravene what we know as physical laws. If they exist, they make possible the otherwise impossible. But the same solution holds – understand how it works, what its limitations are, and how it affects cause-and-effect, and make sure that any relevant information is provided to the PCs trying to solve your mystery.

It’s an additional complication, but one that yields great rewards in the long run.

Some final principles

When you are preparing a mystery – whether for a story or for an RPG adventure – there are some key steps and principles that you should keep in mind.

  1. Where might information be found?
  2. What do these sources know? What will they speculate? What will they get wrong, for reasons of prejudice or other failure?
  3. What do the investigators need to know in order to solve the mystery?
  4. Where can they get that information?
  5. Where Else can they get that information?
  6. What can your players do? What can their characters do? What are their respective strengths and weaknesses? How can you utilize the former to drive the plot forward, and how can you ensure that the latter don’t make it come unstuck?
  7. What will be tedious to play through, and how can it be made interesting?
  8. Mystery plots are inevitably frustrating at some point – how can you relieve that frustration? Will a little random action suffice?
  9. If the players get totally lost, how can you help nudge them forward?
  10. What DON’T you want the players to learn – and how can you avoid it, while still being fair?
  11. How can you make sure that everyone has fun while solving the mystery?

It is in failure to address the first two points that the designer of the module I was GMing, and which I referred to at the start of this article, failed to perform his due diligence. The first item should have turned up the potential for investigation of the Druids, and the second one should have provided the answers necessary to keep the plot rolling along.

One other tip: It helps a great deal with the last couple of items on the list if players can find things out for themselves with their characters, rather than being spoon-fed answers through dialogue!

One Final Technique – and its pitfalls

A technique that I have used occasionally is to create a puzzle without creating a solution. Let the PCs investigate and theorize about possible solutions until you hear one that you like – then expropriate it, give it a slight twist to make it your own, and run with it.

Sounds simple, right? There’s a sting in the tail. If you don’t know where the PCs are going, they can end up painted into a corner. You are not guaranteed that there will BE a solution, after all. You can accept a solution, only to realize, months later – or for a player to realize after such a time-span – that the solution contradicts one or more of the clues that you fed the players and which was overlooked when they came up with their solution.

It gets more complicated – what if, on being confronted, the accused had admitted his guilt – and months later, a line of thought proved that he wasn’t guilty? Why had he lied? Why go to prison, or get executed, or whatever, if he wasn’t guilty? Was he protecting someone or something sufficiently important to justify this sacrifice? Was he misled, or stupid, or forced to confess by back-room interrogation techniques?

What if you’ve lost all your notes in the meantime?
I strongly recommend that if you adopt this technique – which can be an invaluable one – you make DARNED sure that you begin making contingency plans immediately for the possibility that the train will go off the rails at some future point!

Of course, the same thing can happen with ANY mystery if the GM doesn’t get his logic right, so this is good general advice for ANY mystery!


A good mystery can produce greater immersion in the campaign world than any other plotline, but you need to hook the players. It’s a great way to take the campaign background and setting and make it relevant to the PCs. A bad mystery can confuse, obfuscate, and – in general – have exactly the opposite effect. The advice above should help bring you more of the successes and make failures fewer. That’s a good thing, don’t you agree?

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