Chapter 1: Prologue. What happened to Rainbow?
The terrorist organizations were not easy for even the ADVENT Coalition to deal with. They decided to borrow an idea simmering within the minds of the UN: Team Rainbow. They recruited members from all around the globe, and outfitted them with the best gear. But the soldiers' urge to defend humanity from terror led them to the dark truth. They quickly realized they could not fight back; so they ran into hiding, hoping that the latest "terrorist" organization that they had been fighting, X-Com, was not too badly damaged by their efforts. Some even doubted if the first organizations they fought were not evil as well.
Despite this, ADVENT saw an opportunity to profit from the White Masks' existing coordination, and this allowed their fast domination over countries that resisted peaceful joining. It also allowed for the mass-production of standard gear for the human-alien hybrid soldiers, as well as a method of mass-training unseen before on this earth. The psionic network only sped things up.
All the operators managed to make it to local resistance groups, and some groups were fortunate enough to recieve multiple operators. They all helped their resistances in seperate ways; Mute helped his resistance stay quieter, Thermite allowed his group access to more of the supplies in outposts they raided, any many more. But all of them had one thing in common; they could not fight ADVENT head-on. They all did the smart thing; they all waited for the chance to strike.
The chance to strike came to strike for the former FBI operators in America.
As mentioned before, some resistance havens had multiple operators join the same camp; no other camp was a greater example of this than the Boston group. They had the godsend of recieving 4 operators. As luck would have it, this was in range of the official X-com resistance group; together, they devised a plan of attack to free the commander. It was common knowledge that the commander has been taken by the aliens, and, that without his leadership, X-Com quickly succumbed to the alien's attacks. The 4 american operators are now ready to strike against ADVENT, with the first and most important strike yet.