From the frontpage of the module: Once everey 289 years, the Great Modron March passes through the multiverse. It last touched Greyhawk in the Blemu Hills, in the Northern Kindom of Aerdy. Usually, some modrons die. Usually some modrons are left behind. Sometimes the modrons come back for them. This time, they are coming in force, with the fate of an entire village at stake . . . An adventure for APLs 4 - 10.