Editing Big List of RPG Plots (section)

== No One Has Soiled The Bridge==

The PCs are assigned to guard a single vital spot (anything from a mountain pass to a solar system) from impending or possible attack. They must plan their defensive strategy, set up watches, set traps, and so on, and then deal with the enemy when it arrives.
* The intelligence the PCs was given turns out to be faulty, but acting on the new information could result in greater danger - but so could not acting on it, and the PCs must choose or create a compromise.
* The PCs learn that the enemy has good and sympathetic reason for wanting to destroy the protected spot.