Earthshaker! is a humorous scenario regarding a giant mechanical war machine and the factions trying to control it, from the inside. The adventure also covers the player characters attempting to run a dukedom.
The player characters are charged with the responsibility of stewardship over the barony of Vyolstagrad while the baron must attend the king's court. The matters are already difficult with internal and external problems, but then a strange carnival appears with a hugely tremendrous exhibition: A colossal humanoid machine of iron, called the Earthshaker. While the machine itself poses no threat, a band of unscrupulous villains seek to attain control over this iron titan, and only the player characters stand in their way.