Casey was one of several Army soldiers infected with a virus that turns them into werewolves. Casey turned heel after returning home from duty, doing so by forming an alliance with fellow villainous she-wolves Erika and Justine, as they set out on their evil plan to dominate humanity. Their rampage began with attacking onlookers at a local tavern, after one of the customers accidentally ran over Justine.
Later in the film, the evil Casey appeared in her werewolf form, along with Justine, and terrorized citizens in a church. Casey even went as far as to terrorize and berate a frightened young girl, but at that moment, she was shot and killed by one of the hostages.