The first portion of Alpha will have your team simply holding out. After your initial landing and deployment, a pack of Ghouls and Hulks rush the team. After killing them off a large remnant of the Security Team will arrive, and set up a perimeter. The Security Team survivors are composed of Lt. Sheng, a Firebat, and five Marines. After arriving they set up a small perimeter of Sonic Traps.
Alpha Co and their allies will quickly be rushed by waves of zombies, gargoyles, and stalkers. The Security Team Survivors will do most of the work given the players low levels and basic gear. After the last wave of enemies Lieutenant Sheng will tell you the Corpsmen and the rest of his forces are holed up at the Armory. The team then moves out to regroup.