Flames of War is the third book in the best-selling Star Crusades: Mercenaries series that follows the violent struggles of the Alliance, mankind's first interstellar empire.

A new conflict is growing, and it will soon escalate into all-out war. A war that will engulf the colonies of a hundred worlds and could spread to the fragile Alliance. Massive fleets of ships engage in battle, and conflict rages far below on the disputed worlds of the Tenth Quadrant. The valiant defenders desperately need help, but none of the major powers will intervene and risk bringing war to their own territory. There is only one man who will do whatever it takes. A man who will break any rule, and fight any enemy in order to win. His name is Spartan.

Spartan is the Alliance's greatest hero, a titan amongst men and now leader of the elite Interstellar Marine Corps. Tales of his bloody battles have spread throughout the galaxy where they instill fear and praise in equal measure. Spartan plans a private war against the brutal warlord Nakoma, one he intends to win. He calls in mercenaries from every corner of the galaxy, including a group of mysterious Exiles seeking to return to Karnak, a world they still call home. Before they can launch their attack, the enemy unleashes a final, apocalyptic effort to end the war. Can Spartan save the Byotai from the savagery of Nakoma and her legions? Or will the planet fall, and her warriors continue their violent conquest?

The Mercenaries series is set in the aftermath of the apocalyptic Biomech War. The war may have been won, but after nine long years the future still looks bleak. Entire planets remain devastated, and millions of citizens are homeless. It falls on the military, and the growing numbers of mercenaries and freebooters to keep the peace between the great empires and ensure the survival of the overstretched Alliance.