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.

For a thousand years, the Sabbat Worlds have been lost to the Imperium, claimed by the dread powers of Chaos. Now, a mighty crusade seeks to return the sector to Imperial rule. And at the forefront of that crusade are Colonel-Commissar Ibram Gaunt and the Tanith First and Only - better known as Gaunt’s Ghosts. Trapped in the grinding trench warfare of Fortis Binary, the Ghosts find themselves drawn into a conspiracy to assassinate the crusade’s leader, Warmaster Macaroth.

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.

The Peacemaker-enforced ceasefire brought an end to the hostilities, but not a resolution, and now it’s up to the Four Horsemen to forge a lasting peace. Alexis Cromwell, despite her pregnancy, heads off to Capital with Nigel Shirazi to obtain justice from the enigmatic Mercenary Guild Council, but when they arrive, they’re quickly embroiled in galactic politics, and find out the situation is far, far worse than they could possibly have imagined.

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.