The plot by the Galactic Union’s Mercenary Guild against the Four Horsemen has culminated in an invasion of Earth. Faced with an overwhelming force, the human mercs had no choice. They’ve fled, leaving Sansar Enkh to go to the Mercenary Guild headquarters on Capital Planet to stand trial for humanity. On the run, Jim Cartwright and Nigel Shirazi have travelled to the Winged Hussars’ secret base of New Warsaw, in an effort to convince Alexis Cromwell to join the fight, while the other mercenaries who escaped the fall of Earth have gone to the perceived safe haven of Karma.

At a time when Humans were just starting to venture forth into the Galactic Union as mercenaries, Martin Quincy survived long enough to do something no one else had - he retired. There was only one problem: He got bored. After battling aliens for many years - killing aliens and getting paid - retirement didn’t suit him, and he decided to strap on the combat armor and go back to the stars. Along with his old friend Kal, Martin joined Cartwright’s Cavaliers, humanity’s best merc company. Life was exciting! But he got bored. Again.

Heir to one of the leading "Four Horsemen" mercenary companies, Jim Cartwright is having a bad year. Having failed his high school VOWS tests, he's just learned his mother bankrupted the family company before disappearing, robbing him of his Cavalier birthright. But the Horsemen of eras past were smart - they left a legacy of equipment Jim can use to complete the next contract and resurrect the company.

The Hundred Worlds have withstood invasion by the relentless Hok for decades. The human worlds are strong, but the Hok have the resources of a thousand planets behind them, and their fleets attack in endless waves. The long war has transformed the Hundred Worlds into heavily fortified star systems. Their economies are geared for military output, and they raise specialized soldiers to save our species. Assault Captain Derek Straker is one such man among many.

Earth is no longer the center of the universe. After the invention of the faster-than-light jump drive, humanity is rapidly establishing new colonies. But the vast distances of space mean that the old order of protection and interstellar law offered by Earth has ceased to exist. When a nearby world attacks, the new colony of Glenlyon turns to Robert Geary, a young former junior fleet officer, and Mele Darcy, a onetime enlisted marine.