Klassen is first seen in the hanger bay aboard the Sulaco where she and all fellow Marines were fighting Weyland-Yutani PMCs while Corporal Christopher Winter, Private Peter O'Neal and Private Bella Clarison get the UD-4L Cheyenne Dropship ready and evacuate the ship. Klassen also appears at the final battle against the PMCs and the fisrt AA Gun takedown. She covers Winter while he picks up the RPG next to the broken down APC.