Locked Room Mysteries (GUMSHOE Any)

I recently watched a film I'd really wanted to see and came away dissatisfied. I shan't say which one, as this post might constitute spoilers. I'll just say CSI KYC and leave it at that, on the supposition that if you get the joke you've already seen the film and so spoilers mean nothing to you.

Part of my dissatisfaction is because it sets up a locked room mystery and then betrays the trope. The classic locked room is the Mary Celeste of mysteries. It sets up a situation that ought to be impossible, and then shows you not just that it's possible but takes you through the working until you see all the clues you missed along the way. It's called locked room because the classic example is the corpse found sealed away in a locked room, whose death seems inexplicable. Edgar Allen Poe's Murders in the Rue Morgue is the original version, but there have been countless others since.

There have been a few real-life examples. The 2010 death of MI6 operative Gareth Williams, found padlocked inside a bag in his London apartment, is one. Williams, who might have been investigating Russian financial crime at the time of his death, went on leave and never came back. Nobody noticed he'd gone missing until his employers thought to make a welfare check, which is when his corpse was discovered. It's thought he went into the bag alive and the Metropolitan Police concluded his death was probably an accident, a sex game gone wrong. As a means of disposing of a body locking it inside a sports bag and leaving it in the flat seems unnecessarily theatrical, almost amateurish, especially if a professional espionage agency was involved. You'd think it'd be simpler to dump the bag in the Thames with weights wrapped round it. It's that Mary Celeste touch again - cups of coffee found still warm in the wardroom, everything apparently normal except there's no crew aboard.

The thing about a locked room is, it's never impossible. It's a puzzle box, and there's always a way to solve a puzzle box. The key is to disbelieve what's in front of you. The minute someone says 'judging by blood splatter, the only way it could have happened is ...' you know for a fact that, whatever else happened, the so-called only way is precisely how it didn't happen. A locked room works on magician's rules, and a magician's favorite trick is misdirection.

So if a corpse turns up in a burnt-out garage, for example, and dental records show that the corpse is Mister Bob Bingo who owed everyone a ton of money, then your first job is to look at those dental records and see if they're fake. Trust nothing, check everything.

As it's a puzzle the emotional satisfaction comes from solving the puzzle, and if the thing's badly designed or if the author cheats their way to a solution then the fun's lost.

Example from CSI KYC: at one point a poison's described as being lethal inside ten minutes. The characters go to a great deal of trouble to establish this. Then in another scene the same dose takes two hours, and even then the victim isn't dead. Which is it? 

In game, how would this work?

Remember this: once you introduce magic, or super-powers, or whatever it may be, the puzzle stops being a puzzle. The audience - the players - will assume magic did it. The problem switches from 'how does the puzzle work' to 'how do I show the solution isn't magic?' At which point you've probably lost the most important battle: capturing the audience's attention. 

So set the puzzle up in such a way that magic isn't the first or obvious answer. Maybe this is a Mutant City Blues game in which the necessary mutant abilities don't fit well into the Quade Diagram, or perhaps this happened during the day when vampires are powerless. Something quick, simple and obvious, so you can get on with the plot. This is why abilities like Night's Black Agents Vampirology are so useful, because one point spend will tell the agents 'a vampire couldn't have done it, at least not the way it was done,' without the Director jumping through hoops to show it wasn't vampire magic.

The best way to design a puzzle like this is to start with the solution and work backward. If you know who did it and how they did it then you should be able to come up with clues that show as much. Always remember this is a puzzle, and puzzles can be about anything. It doesn't have to be murder. It can be 'how did a virus get onto the system when it's not connected to the internet?" Or 'how did that burglar get into this hidden safe?'

Let's play with an example. Assume the setting is Night's Black Agents, modern day, so we're talking every conceivable current technology. Let's further assume that the crime takes place in an area patrolled by security robots which ought to have detected the intruder but did not. It doesn't matter what the crime is. The puzzle is how whoever did it foozled the security robots so they weren't detected carrying out the crime.

The software that operates the robots and monitors their activity reports no anomalies at the time of the crime. The incident reports show only that there was a brief interruption in patrol when a human employee fell ill. The robot stopped to monitor the situation and summoned a security guard, who confirmed that the person suffered a bad reaction to allergy meds. The sick person was escorted away and treated. 

The hardware that runs the show is not connected to the internet or the outside world. It's a purely internal network whose sole purpose is to run the building. It does everything from monitor the security robots to adjust the HVAC and make sure the goldfish tank in the exec suite is operating smoothly. Employees are expressly forbidden from attaching their own devices to the network, or using company property like laptops outside the building. There's no indication (via internal monitoring) that anyone did connect an outside device to the network, whether on the day or at any time in the past. So there should be zero chance of a virus corrupting the system. The hardware is in a security room down on the ground floor that is constantly monitored by cameras, sensors and human security personnel. 

So how was it done?

A virus was introduced into the system that prevented the security robots from detecting the intruder, or anyone at all, after a certain point. The target room and the corridors immediately around that room became invisible zones; the security robots could not see humans while they were in those zones. The agents may become aware of this when they realize that the robots did not detect the CEO even when he was in an area where he ought to be detected. He was working late on a big project, which is why he was in the building. 

How was the virus introduced? By our old friend the fish tank. 

The thermostat was recently replaced on the CFO's authority. That thermostat was the Trojan Horse which introduced the virus to the system. The CFO is the employee who had the bad reaction to allergy meds, which coincidentally enough happened at about the same time as the incident. The CFO doesn't remember authorizing the thermostat switch.

The CFO didn't authorize the switch; her secretary did. Turns out the CFO was poisoned by her secretary to create a diversion so the secretary could carry out the crime. While security and the robots were diverted the secretary got into the invisible area. She used 'I'm going to get your meds' as an excuse to leave the CFO's side and carry out the crime. The whole thing took five minutes.

So how would you do it?

Enjoy!