Approximately 30 years before the beginning of the novel, a small group of alien refugees (later termed the "Gurus") landed on Earth and soon made themselves indispensable with their contributions to human technology and scientific understanding.

In exchange, they "requested" Earth's help in repelling the hostile invaders (termed the "antagonists" or simply "Antags" or "Ants") who had chased the Gurus from their own star system, and were already establishing a beachhead on Mars.

The narrator of the novel is Master Sergeant Michael Venn of the multi-national force of "Skyrines" (spaceborne Marines) sent to Mars.

Venn returns home from his last tour of duty on "The Red" (Mars) and settles into his apartment in Seattle, Washington, remembering the events of that tour: Venn and his squad's combat drop onto Mars goes badly wrong after their fleet is attacked in orbit by the Antags.

They are unable to establish contact with other elements of their force or their commanders, nor can they receive any intel on the enemy's numbers or locations.