At an unspecified date in the 21st century, humanity has become engaged in a 25-year-long war with an unidentified alien species that have become known as the "Couatl." Humanity had captured several Couatl starships and began reverse-engineering them to no avail. After recovering from a previous engagement, a hardened veteran Major Stockman returns to active duty with an unit of rookies. The unit is given an assignment regarding an all-out fleet engagement within a few nearby star systems infested with Couatl forces. During the engagement, Crose with a young recruit named D'Ambrosio.