For the specific incident where I discovered this technique, read my session notes here.
A Helpful Metaphor
You can think of a campaign as two timelines. Timeline #1 is your mental plotline for the campaign, based not only on what you want but on what the players seem to be interested in. This timeline is easily rearranged – you can always change something you’d planned for the PCs to do (as long as it’s still in their future). It’s also sketchy – you may have a general idea where you want the campaign to end up, but you’re waiting to discover the details about getting there.
Timeline #2 is your group’s actual, in-game story progress. Your geekiest player probably bas a handwritten copy of timeline #2 in his binder. PCs make certain choices, establish relationship with NPCs, and you declare certain consequences. This plotline can’t be rewritten once it’s happened. Ideally, timeline #1 gets developed in your head, and then fleshed out as you play timeline #2.
When you’re GMing, you are the point of contact between these two timelines: you’re trying to bring elements from timeline #1 into play in a way that squares with what’s happening at the current moment in timeline #2.
Sometimes the timelines don’t match up. Let’s say in timeline #2, it’s the right time for your players to get an Important Clue about the next plot point (maybe they’ve just defeated an NPC who clearly knows something). Now, in timeline #1, you know what that plot point is (a piece of information that will lead them to discover the name of the Evil Council), but you haven’t decided whether it’s in the Lowest Level Of The Notorious Prison For The Insane, or whether it’s on the Jungle Island Full Of Superstitious Natives And Carnivorous Plants. You’ll ultimately pick one or the other based on what the players seem interested in and what they’ve already had enough of, but for now you don’t know.
Resolving The Clash
Making that Important Clue into a “Russell’s Map” is your way out of this bind. Go ahead and give them the Important Clue (could be a map, an inscription, an NPC testimony, a book, etc.), but if it’s a map, make it so they can’t tell what part of the world it’s in. Or if it’s an inscription, make it an unsolvable riddle. If it’s an NPC testimony, it’s a codeword even the NPC doesn’t understand. If it’s a book, it’s in another language. The PCs will have to spend some in-game time finding a way to deciper it, which will give you enough real-world time to decide what, exactly, the clue should be.
This is a bit of BS, granted. “Uh, you don’t know what the map says so you better try reading it again in a few sessions.” (Scribbles in notebook furiously.) But if you sell it right, it relieves you from having to come up with something on the spot, in a way that still tells the players where they need to go next (“the map style is so ancient that it would take an expert cartographer to make sense of it!”) and most importantly it doesn’t render the clue unimportant. After all, if the party has to do a sidequest to make use of the clue, it must be really important!
Turning an Important Clue into a Russell’s Map fulfills the mandates of timeline #1 and #2 – the party has the Clue, but won’t be using it until you’ve had some time to figure out what it should, according to what your players want out of the story, do.
When The Clash Comes From Ad Lib
One of my favorite parts of GMing is when the players do some spontaneous world-building. I might give them the name of a place and they say, “Ah, I’ve heard the legends. They say that…”
This gives them a chance to tell me what they’d like to encounter and does a good bit of my work for me. But it can also be risky. The original Russell’s Map was an item that a character had in their possession, as a minor part of their character story, that they didn’t know where it led. Now, if I’d had a Key Plot Element in mind, like a book or an inscription, I could have simply transplanted that same information onto the map – presto, the player’s contribution leads to something important as if it hadn’t taken me by surprise at all. But since I didn’t have such a Key Plot Element prepared, I just made his map into a Russell’s Map, with lots of colorful description about why it was unreadable – colorful description that clued them in that they might need an antiques expert to read it.
Another time ad-lib can get you in trouble is when players don’t know they’re ad-libbing. That’s right, when they focus on a random detail in ascene, thinking it’s a plot-relevant piece of information. Here again you won’t know where that random detail leads (because it doesn’t lead anywhere… yet) but you can reward and build their interest by making it lead somewhere. If, again, you don’t have a Key Plot Element you can swap it out with, make the item a Russell’s Map; let them make an investigation roll, give them a colorful description of why they can’t make head or tail of it, and buy yourself some time.