The story unfolds in the earliest, most desperate days after Emergence Day, the catastrophic moment when the monstrous Locust horde first erupted from beneath the surface of the planet Sera to seize humanity's cities. Amid the chaos, a small band of soldiers known as Kilo Squad, led by the sharp-tongued mechanical genius Lieutenant Damon Baird and including the boisterous former athlete Augustus Cole, fights to survive as the Locust overrun the coastal city of Halvo Bay. The tale is told through flashbacks, framed as testimony delivered before a stern military tribunal, where Kilo Squad stands accused of grave crimes. As each member recounts their version of events, the harrowing story of their defiant stand against the invading horde, and the fateful decisions that landed them on trial, gradually comes to light.