On July 2, a giant alien mothership enters orbit around Earth and deploys several dozen saucer-shaped 'destroyer' spacecraft that quickly lay waste to major cities around the planet. On July 3, the United States conducts a coordinated counterattack that fails. On July 4, a plan is devised to gain access to the interior of the alien mothership in space, in order to plant a nuclear missile.
In the year 2524, four centuries after humans started colonizing the outer planets, retired General James Ford gets called back into service when a hostile alien fleet attacks soldiers on a remote planet. The threat against mankind soon escalates into an interstellar war as Ford and a team of elite soldiers try to stop the imminent attack before it's too late.