The classic murder mystery: a bunch of eccentrics gather, often at a remote house or other confined location, and then – thump! One of them’s murdered.
In most roleplaying scenarios, red herrings aren’t needed. The classic advice is that the players create enough confusion as they maraud and blunder towards a conclusion that adding distractions isn’t needed. In a whodunnit, though, the murderer is usually close at hand the whole time, so you need to give the players a list of suspects. (The murderer doesn’t have to be one of the initial suspects, of course, but the investigative path to the murderer leads through the suspects).
For each suspect, come up with two or three clues that point towards their guilt. Use the classic means/motive/opportunity triad. Each of these initial clues suggests a reason why they might have committed the crime, or puts them near the scene, or implies they have the tools or capability to carry out the murder.
- Opportunity is the trickiest to handle, as it locates the suspect in time and space. (The butler saw Lucy near Martin’s bedroom on the night he was murderer.”)
- Means is the second trickiest – if the murderer was killed in a distinctive manner, then it can be hard to come up with benign explanations for a particular means. (Martin was stabbed with a knife, and you know that Lucy always carries her mother’s ornamental silver letter opener with her.)
- Motive’s usually the easiest, as it can be remote in time and space. (Asking around, you learn that Martin and Lucy had an affair in college, and she always resented him afterwards.)
The investigators get these clues early in the scenario.
Then, for each of these clues, come up with a second clue that does one of three things.
- The second clue exonerates the suspect completely, eliminating them from consideration completely. (Classically, this can also be done by killing off the suspect).
- The second clue deepens suspicion by further implying the suspect’s guilt.
- The second clue points to a subplot.
Subplots are key to a good murder mystery scenario. If the only line of investigation to be followed is “who killed the victim”, then either the players will zoom through the chain of clues quickly, or you’ll need to make the chain so long and convoluted that it beggars belief. (In a supernaturally-tinged setting, you’ll generally have a supernatural plot for the players to dig into and the murder is just the initial hook, but a classic murder mystery is all about the murder).
The subplots are the reasons why all the other suspects are running around being suspicious and uncooperative. Maybe they didn’t kill the victim, but they’ve got other secrets to hide. To return to Lucy and the late Martin, let’s take each of those clues in turn and add in a second clue.
1st Clue (Opportunity): The butler saw Lucy near Martin’s bedroom.
2nd Clue (Exoneration): The butler’s discovered to be a notorious drunk who imagines things.
2nd Clue (Deepening Suspicion): Searching Lucy’s room discovers a blood-soaked nightdress.
2nd Clue (Subplot): Under questioning, Lucy admits that she was near Martin’s bedroom – because she went to say goodnight to Martin’s brother Fred.
1st Clue (Means): Lucy carries her mother’s letter-opener wherever she goes.
2nd Clue (Exoneration): The letter-opener doesn’t match the wound in Martin’s body.
2nd Clue (Deepening Suspicion): Lucy claims to have lost the letter-opener in the garden, even though she’s cherished it for years and never leaves it out of her sight.
2nd Clue (Subplot): The letter-opener shows up in the window of the village pawn-shop – why is Lucy so desperate for cash that she’s sold her beloved knife?
1st clue (Motive): Lucy had an affair with Martin that ended badly.
2nd Clue (Exoneration): Talking to Lucy’s best friend confirms it was just a youthful fling, and that she never resented Martin enough to murder him.
2nd Clue (Deepening Suspicion): The investigators discover a cache of anonymous threatening letters that make reference to Martin’s college days.
2nd Clue (Subplot): Questioning Fred reveals that the reason his brother and Lucy broke up is that she and Fred became involved. But what’s Lucy’s current relationship with Fred…
Solving a subplot leads to more clues that exonerate or deepen suspicion for other suspects (or add more suspects to the suspect list). For example, in the growing Martin-Fred-Lucy imbroglio, the investigators discover that Fred persuaded Lucy to pawn the knife for money, because Fred was trying to pay off his brother’s gambling debts – which adds the sinister bookmaker Alphonse to the mix. Did Alphonse somehow convince a guest at the dinner party to murder Martin over unpaid debts?
By the end, everyone’s exonerated, except one person who (however improbable) must be the killer.