Jack O'Sullivan serves among human military forces deployed to Earth for operations against Godzilla. He is part of Company A, which incurs heavy losses during a Servum subspecies attack while establishing a planetary base camp. After the assault, O'Sullivan and fellow Company A survivors merge with other human units under Elliot Leland’s command. The combined group crosses territories ruled by Godzilla and its subspecies to arrive at an appointed rendezvous point.