It is the fall of 2045. Aizawa Shuuhei, a second-year military cadet, is sent on a training mission to Aries, an orbital space station. There he finds his younger brother Ryouta and his childhood friend Nao, both enrolled in the station's preparatory division. Then the terrorist organization Jararacas launches a sudden assault on the Aries, seizing the main control room and cutting all communications. Two hundred and fifty miles above Earth, with no way out, the cadets have only one option: take the station back themselves. As they fight back, the true reason behind the attack begins to emerge.