In most mysteries, the investigator’s discovery of the crime restores the world to rights. The detective figures out that the butler did it, and the police arrest the murderer. The crime and its cover-up are an aberration, and uncovering them means the laws and morality of wider society can reassert themselves.
The Cthulhu Mythos doesn’t work that way. If your investigators discover that the Mi-Go murdered Henry Akeley and stuck his brain in a cylinder, then calling the Townsend county sheriff won’t achieve much other than adding a dead sheriff. Inhuman or cosmic forces of the Mythos care nothing for human authority.
So, when designing a Trail of Cthulhu scenario, you need to consider two distinct but intertwined elements – the mystery and the problem. The mystery is ‘what went on or is still going on?’, while the problem is ‘what do the investigators do about it?’, given that exposing the villain’s crimes and going to the authorities doesn’t work.
Note that most Mythos stories, as opposed to roleplaying scenarios, don’t need to worry about having both a problem and a mystery. Many of Lovecraft’s protagonists exist purely to uncover the horror and then die, flee, go mad or otherwise recoil, and don’t actually do much problem-solving. However, the nature of roleplaying games demand that the players be more than passive clue-followers.
- Simple Survival: The investigation into the mystery puts the investigators into danger, and they’ve got to escape or survive. This is the plot of At The Mountains of Madness – the Miskatonic expedition encounters the mystery of the lost city of the Elder Things, and uncovers their history and awful fate, but then has to escape the Shoggoths they created. Simple survival needs a clear endpoint, like “getting to the airplane” or “surviving until the dimensional conjunction ends”.
It’s hard to make Simple Survival into a satisfying investigative problem; it tends towards the action-packed, which means lots of running and jumping and shooting and General Ability tests. It also runs the risk of making the scenario feel a little hollow, as the best course of action for the investigators would be not investigating the mystery in the first place. To make it satisfying, tie it to the investigator’s Drives and make sure that the mystery part is worth the trouble.
Clues to be found: where can the investigators find safety? How can they delay or hide from the threat?
- Escape the Curse: The investigators have already been exposed to some awful force, and need to find a way to free or cure themselves. A scenario based on, say, The Colour Out Of Space might use this setup – the investigators get tainted by the colour early on, and need to discover a way to banish the horror before it consumes them. The downside of this problem is that you do need to engineer events early in the scenario to ensure that some of the investigators get afflicted, but that’s easily forgiven if the curse is memorable and compelling. It’s a great setup for drives like In The Blood.
Clues to be found: How can the curse be broken? What actions do we need to take, or items to gather?
- Come to Terms with the Horror: A more subtle, Purist problem – there’s no escape from the Mythos threat, but the investigators can learn to understand and accept it. To a degree, this is the plot of part of The Shadow out of Time or The Shadow Over Innsmouth – there’s no victory, only acceptance. This can work very well for one-shots, but rarely suits episodic games unless your group handles the occasional cryptic anticlimax.
Clues to be found: What will happen to us? How have other people come to terms with this in the past? How can I resolve my emotional ties before the horror consumes me?
- Save The Victim: This works like Escape the Curse, but instead of the investigators running afoul of the Mythos, it’s some sympathetic relative or acquaintance (“you get a letter from an old friend”) – or the investigators are hired by someone to help a victim they don’t know. The Thing on the Doorstep uses this set-up, to a degree. This setup works very well, but runs the risk of empathy fatigue – the players might care about one hapless old friend that’s in danger, but once you’re onto the sixth old friend, cynicism takes hold.
Clues to be found: How can the threat to the victim be averted? What actions do we need to take, or items to gather?
- Thwart the Foe: This is Pulp territory, where the Mythos can actually be defeated. The Dunwich Horror is the classic model here, although The Case of Charles Dexter Ward also fits. The problem is finding some magic or tool that will destroy the threat or foil their evil plans (Ye hoary old “stop the ritual” plotline, for example). While this problem works really well for a game, it can come across as stale or predictable, and also pushes the investigators towards a particular solution. If the only way to defeat the Hunting Horror is to find the spell that dismisses the Hunting Horror, then the problem is just ‘follow the clues to find the spell’ – so you need to make those clues and the act of following them as interesting as possible, or have a secondary (non-Mythos) mystery or problem to solve.
Clues to be found: How to we wield the power of the Mythos against the Mythos?
- Contain the Threat: This is similar to the ‘thwart the foe’ problem, but doesn’t pre-suppose a Mythos-based solution. Often, the problem involves reversing whatever was done in the mystery (“the murdered archaeologist took the idol from the tomb – so we’ve got put it back”) or just brushing the threat under the carpet, geologically speaking (“we blow up the mine! We demolish the haunted house!”). The trick here is giving the players a good idea of the nature of the threat without robbing the Mythos of all strangeness.
Clues to be found: What are the weakness or limitations of the threat that we can exploit?
- The Mythos Was Never The Problem: Here, some aspect of the Mythos perturbs a human situation, but the challenge is not defeating the Mythos – it’s unravelling the human elements of the plot. Take the example of a criminal who has bargained with the Deep Ones to help transport bootleg rum – the investigators don’t need to find a way to stop the Deep Ones, they need to stop the gangster, and the Deep Ones will sink back into the unknowable deeps.
Clues to be found: Varies wildly, but often involve lots of Interpersonal abilities.
- Actually, Go To The Authorities: While most aspects of the Mythos are beyond human authorities, that’s not universally true. The Shadow Over Innsmouth, for example, finishes with the protagonist reporting the situation of the corrupted town to the federal government. The problem in this case is finding proof and getting it to those with the power to act.
Trail of Cthulhu is an award-winning 1930s horror roleplaying game by Kenneth Hite, produced under license from Chaosium. Whether you’re playing in two-fisted Pulp mode or sanity-shredding Purist mode, its GUMSHOE system enables taut, thrilling investigative adventures where the challenge is in interpreting clues, not finding them. Purchase Trail of Cthulhu, and its many supplements and adventures, in print and PDF at the Pelgrane Shop.