Detail that convinces
One of the most delicious uses of detail is that you can make anything convincing. Before you shear off any wild idea as too crazy or too unrealistic, see if you can keep the idea and heap on the detail that will make it convincing. Remember: stories don't have to be realistic, just convincing.
If you're already writing with these prompts, use what you've developed of your story so far. If you're just starting here, use this premise, Why did the protagonist fake those maps? and take a few minutes to thrash it out. Here are some questions to help: Who's the protagonist? What maps did they fake? Why? Where were the maps of? Who wanted them? Why were they needed? What happened because they were faked?
What's the most unlikely aspect of your story idea? Keep that: don't prune it down to make it more likely, heap on the detail instead. Use these prompts to scheme away at it, through brainstorming or speedwriting, whichever you prefer. Think about... how it works, in detail • why it works, in detail • precise terminology, facts, & figures • the process • observe every texture / sensory detail closely.
For more on Detail, you can download Story Elements: The Complete Set - only available until 30 December 2014. Find out more, see previews, and download it here.