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.

In the 20th century Earth sent probes, transmissions, and welcoming messages to the stars. Unfortunately, someone noticed. The Galactics arrived with their battle fleet in 2052. Rather than being exterminated under a barrage of hell-burners, Earth joined their vast Empire. Swearing allegiance to our distant alien overlords wasn't the only requirement for survival. We also had to have something of value to trade, something that neighboring planets would pay their hard-earned credits to buy. As most of the local worlds were too civilized to have a proper army, the only valuable service Earth could provide came in the form of soldiers....

Captain Keyes is loved by the public but hated by Command. He captains the UHS Providence, an aging supercarrier and the last human ship not dependent on dark tech - technology humanity has used to rule over the galaxy since barely defeating the Ixa in the First Galactic War. Dominance has come at a cost. Over the decades, old allies have grown resentful, and when dark tech itself fails, Captain Keyes’ predictions start coming true: those old allies are now enemies.

They hunt us. They bomb our worlds for target practice. A star cluster in the constellation of Orion rotates once every 1,000 years. Those who rule there have an ancient tradition: When each cycle ends, they train their fleets by spilling the blood of lesser beings. The enemy fleets are coming again. In response, the Rebel Worlds gather their starships to face the terrifying threat, and this time humanity is asked to stand with them. The last time they considered Earth, Vikings in longboats were raiding English coastlines. Today, we're less primitive. Today, we're a target.

Years after defeating aliens bent on burning down the galaxy, the Interstellar Union is breaking apart, its member species undermining each other at every opportunity. When an interdimensional distress signal arrives, only humanity is interested in helping. Captain Vin Husher is given command of the UHS Relentless, and sent in as part of a carrier strike group...right into a trap laid by humanity’s old enemy. Surrounded by a bioengineered super-species and unable to return home, Husher must draw on decades of experience just to keep his people alive.