The French Arm is the most heavily-settled and best-developed segment of humanity’s extra-solar expansion, thanks to the efforts of the ESA member nations. In 2295, a research station studying the red giant star Arcturus made contact with an unknown starfaring species. Attempts to communicate were fruitless, and the alien flotilla departed the system after a few days. One year later they returned. Invasion is a complete campaign covering the war against the alien Kaefers. The Travellers are swept up in this conflict, and find themselves becoming heroes. Included are descriptions of all colony worlds on the French Arm, the major outposts, new spacecraft, a compilation of animals and characters, and information on three alien species. Also included is a large section detailing Station Arcture. All of this supports a campaign that follows the Travellers from humble beginnings as colonists on Aurore caught in the first alien assault, then across worlds of the French Arm. The focus is on the Travellers and the worlds and people they meet, showcasing the horror and heroism of an interstellar war for survival against a mysterious and terrible foe.