How to Design a Mystery Adventure

[CaptainCharisma]

So, I'll be running a mystery style adventure with my group in which they ultimately do not have a 100% chance to actually solve the mystery. The basis for this mystery is that, nightly, the ghost of a dead farmers wife is raising from the church graveyard and roaming the streets. In her presence, the recent and not so recent dead raise, and while they don't really do anything unless disturbed, having undead just sitting around during the night kinda makes everyone uneasy.

Also, Doc and Brian, I know you guys browse this forum, no reading!

There are three planned outcomes that the PCs can reach;

1. They simply rid the town of the ghost. I'm thinking either burning the body, preforming a powerful cleansing ritual on it, or some other such thing. 'Beating it down' will simply disperse it for the night, and I don't see them beating it down because of the parties capabilities and level.

2. They figure out that the farmer actually killed his wife and staged it to look like wild animals had killed her.

3. They figure out the farmer is bewitched by his new wife, who is actually a hag in disguise (I'm thinking green hag, as they take pleasure in just messing up things). Under her control, he killed his wife, hid the body, and then shortly after married the new girl, allowing her to insert herself into society and potentially wreak more havoc. Said hag is actually part of a wide reaching coven who's objective I haven't quite determined yet.

The single biggest clue will be the dark sacrificial altar under the farmers house. There will be a trapdoor into the cellar, hidden under the rug. The cellar itself isn't out of the ordinary, except the PCs will be able to find the murder weapon thrown down there. Behind a shelf in one corner will be a small tunnel, leading to a chamber containing the altar, along with a scrying device of some sort. Other than that, I don't really know how to lead them along effectively to create a good mystery. Mystery was not the type of books I usually read, so I don't have a ton to pull off of.

What suggestion do you guys have for clues?
The party does have some decent observation and social skills, so what would you suggest to make it challenging, but not unable to figure it out?
How would you all lay this out, personally?

For reference, the party is level 3, consisting of an open hand monk, a dragonblood sorcerer, a trickery cleric, an ancients paladin, and there SHOULD be a rogue of some sort joining in this next session.

[Ninja_Prawn]

Well, some general pointers:

Avoid bottlenecks. Especially ones that depend on getting good dice rolls at the right time.
Have three clues to each important discovery
Avoid red herrings. If the players get distracted, you can waste a lot of real-life time. And players won't believe you when you tell them it's a red herring.
Give pointers before they roll perception/investigation. Because they might just decide not to investigate a given room at all.
Be prepared to move clues from one place to another. Shrödinger's clues!
As for specific ideas...

So there are two truths you want to get to here: the new wife is a hag and the farmer killed the old wife. So, if I just take the first one, the end revelation gets three clues...

New wife is a hag. Clues: she has an aura of illusion magic (the cleric can cast Detect Magic), she sometimes disappears into the swamp for days at a time, and she once tried to kidnap a baby (if any of them have a high passive intelligence (nature) score, you could flat out tell them that's something hags are known for).

And each clue gets three clues...

Aura of illusion magic. Clues: a travelling salesman comes into town and auctions a wand of detect magic; she furiously outbids everyone then hides it away, a crazy beggar accosts the party to tell them that he sees swirling magic around her, and there's a small dead magic zone in the centre of town that she avoids like the plague.

Disappears to the swamp. Clues: some drunkards are gossiping loudly about it at the tavern (or wherever the party goes that it would make sense to have drunkards), there's a well worn path from the farmhouse to the swamp (which you flat out tell them is odd; their characters would know townsfolk have no business in the swamp), and her house is full of rare swamp plants (that she tells them she gathers herself; it's okay to have one or two obtuse clues when you're giving out nine).

Tried to kidnap a baby. Clues: the parents publicly accuse her, an orphan claims to have witnessed it, she has an empty crib that she frequently stares at when she thinks no one is looking (or something).

So now you have nine clues, and most of those are things you can throw at the party pretty soon after they arrive in town, so perhaps that's as far as you want to go. The most important thing is to have three pointers to each revelation, not have three clues in each location the players go to (which has been the received wisdom for years). Players will stop looking after they find one clue, and if they decide not to check a certain location or roll badly, you've just lost three clues. At least, that's what I think.

[Cybren]

Recommended reading: http://www.sjgames.com/gurps/books/mysteries/

[Ghost Nappa]

Make sure when you get into the details of your story that you're following Fair-Play. (http://tvtropes.org/pmwiki/pmwiki.php/Main/FairPlayWhodunnit) Given the medium, it's hard to make some of the pitfalls of violating fair-play.

I also suggest you make an Investigator-Watson fill-in to help both act as a mouth piece for some exposition bits and to also offer the party an out if they decide they don't want to do an mystery quest anymore.

[mgshamster]

One of my friends has a custom set of rules for games like this.

I just texted him, and here's what he said:

Basically you take the "investigation skills" and instead of having to roll for them as long as the player says "Oh, I'm using my... pfffft... Toxicology skill." The DM gives them basic information.

"You can tell by the coagulation of the blood that there was a specific poison from the [coagulation] family used on this victim"

But then instead of skill points they have a Toxicology "Pool". So if they have Toxicology 2 then twice per game (or session, day, week, month, whatever), they can say "I use one of my toxicology pool points"

And the DM gives them addition information: "During your investigation you find evidence to believe it was [specific plant] that was used, and it would have been used sometime around 30 hours ago exactly."

So the players get additional leads for spending those points.

It's an alternate solution to the idea of trained professionals rolling a 1 and having no idea of a basic thing they should have seen 100 times sort of thing. It has its own inherent issues but I like it for the style of game I enjoy.

[Aelyn]

Basically you take the "investigation skills" and instead of having to roll for them as long as the player says "Oh, I'm using my... pfffft... Toxicology skill." The DM gives them basic information...

But then instead of skill points they have a Toxicology "Pool". So if they have Toxicology 2 then twice per game (or session, day, week, month, whatever), they can say "I use one of my toxicology pool points"

And the DM gives them addition information: "During your investigation you find evidence to believe it was [specific plant] that was used, and it would have been used sometime around 30 hours ago exactly."

This is the core mechanic in Trail of Cthulhu (a mystery-horror game I've been playing recently) and I can attest that it does work well for a fair-play mystery, especially a relatively roleplay heavy one.

As you say, it's a good way of avoiding the "my druid's never heard of mistletoe" problem. Only issue is that I'm not sure how best to implement it in D&D - the ability to take 10 on a proficient skill check is a good starting point, I think.

[CaptainCharisma]

This is the core mechanic in Trail of Cthulhu (a mystery-horror game I've been playing recently) and I can attest that it does work well for a fair-play mystery, especially a relatively roleplay heavy one.

As you say, it's a good way of avoiding the "my druid's never heard of mistletoe" problem. Only issue is that I'm not sure how best to implement it in D&D - the ability to take 10 on a proficient skill check is a good starting point, I think.

No, taking 10 should not be in this system, as the ability to Take 10 is an actual class ability of the Thief Rogue. Allowing other classes to do it isn't fair. Usually, I just don't make them roll for certain things. A druid WILL know what mistletoe is. There is no chance for failure, unless the druid is from, say, a desert or something.

[Ethambutol]

No, taking 10 should not be in this system, as the ability to Take 10 is an actual class ability of the Thief Rogue. Allowing other classes to do it isn't fair. Usually, I just don't make them roll for certain things. A druid WILL know what mistletoe is. There is no chance for failure, unless the druid is from, say, a desert or something.

I allow take 10/20 in situations where there is no time pressure and the character/party is willing to commit a significant amount of time in order to accomplish a task.

For example, if a member of the party is a detective and is carefully investigating a crime scene and is willing to spend the better part of a day carefully picking the room apart for clues, I'd allow for a take 10 (or even 20) if they're proficient with investigation. If they want to deduce what they can from a quick run down, then they'll have to roll and pray.

If they foolishly decide to take time in order to take 10/20 when they do in fact have time pressure, then well... there are consequences to delay.

[MrStabby]

Also allowing people to take 10 when the level of play is below level 10 doesn't diminish the ability.

[Specter]

What's very important to do in these cases is to make sure skills get good use. If the farmer is acting weird, Insight check. If there's a bloodstain that has been cleaned off and left a slight stain on the floor, Investigation. Two reasons:

1) Players can be very dumb in a unilateral solution module, especially the players that only care about combat or that are piling up dice while you describe the scene.
2) Players (good players) will be upset if they build their characters for investigations, tracking, knowledge, etc. and not get their mechanical advantages.

[Ninja_Prawn]

I allow take 10/20 in situations where there is no time pressure and the character/party is willing to commit a significant amount of time in order to accomplish a task.

Shouldn't that just be a passive check?

[Ethambutol]

Shouldn't that just be a passive check?

I mean, essentially yeah. A passive check is by definition a take 10 isn't it?

[Aelyn]

No, taking 10 should not be in this system, as the ability to Take 10 is an actual class ability of the Thief Rogue. Allowing other classes to do it isn't fair. Usually, I just don't make them roll for certain things. A druid WILL know what mistletoe is. There is no chance for failure, unless the druid is from, say, a desert or something.
I assume you're referring to the Reliable Talent trait? It's a feature of all Rogues, but it's significantly better - you can still roll and treat a result of 9 or lower as a 10. My suggestion is just taking 10, which doesn't allow the possibility of a high roll.

[Spiritchaser]

I started a campaign once where everyone regained consciousness on an isolated island, with no memories, and with a dead body on the floor. Beforehand I'd had each of them roll up multiple character backgrounds that they'd be happy with, their personalities had to be similar in most respects but one of them had to be evil. No-one knew exactly who their own characters were.

I had a lot of fun, as did the players but I learned that I need to get much better at running that kind of thing.

1. Players WILL get a hold of a red herring and clutch firmly to it. Have a plan to dissuade them
2. If you gate discoveries behind skill checks, then you need to find multiple ways to communicate the information. This is a fantasy world so there are lots of foils for this.
3. Sometimes breaking the mystery with a tangentially related distraction with something else can actually be good. My island had pirates... Actually lots of my adventures have pirates, so that doesn't necessarily have much meaning.
4. If you can find a way to gate things behind a timeline of natural events that will occur (daylight, poison wearing off... low tide) you can make a small and manageable area more dynamic.

Just my two cents. I need to read through all the other replies to this as well... I'd love to do another mystery.