Operation Overlord is the American Marine assault on the Kafer citadel based at Dunkelheim. The adventure follows a group of American Marines from their interface assault landing through a mission which takes them into the heart of the Kafer "Ch*!!"

This book contains information on the colony world of Dunkelheim and the citadel which serves as the Kafer "Safe Place." This book also contains extensive information about American Marines, their equipment and their organization.

A modified skills list is even included for characters who enter the career path of the Corps. Finally a brief update on the Kafer War is provided, describing the disposition of naval forces and of the American Marines following the completion of the adventure.