Erik Cain joined the Marines to get off death row. The deal was simple; enlist to fight in space and he would be pardoned for all his crimes.

In the 23rd Century, assault troops go to war wearing AI-assisted, nuclear-powered armor, but it is still warriors and blood that win battles. From one brutal campaign to the next, Erik and his comrades fight an increasingly desperate war over the resource rich colony worlds that have become vital to the economies of Earth’s exhausted and despotic Superpowers.

As Erik rises through the ranks he finally finds a home, first with the Marines who fight at his side and later among the colonists – men and women who have dared to leave everything behind to build a new society on the frontier, one where the freedoms and rights lost long ago on Earth are preserved.

But causes can be fleeting, imperfect things. Amidst the blood and death and sacrifice, Erik begins to wonder. Is he fighting the right war? Who is the real enemy?

The Third Frontier War is raging, and all across human-occupied space worlds are burning. Massive fleets struggle for dominance and kilometer-long war ships exchange thermonuclear barrages.

Battered in the early years of the war, the Western Alliance is resurgent. The brilliant Admiral Augustus Garret leads the Alliance fleet from victory to victory, taking the war to the very heart of the enemy empires.

On the ground, Colonel Erik Cain, hero of the Marine Corps, leads his crack troops again into combat, seeking the final battle, while in the background, the secretive intelligence agencies of the despotic Superpowers plot and scheme, using their own soldiers as pawns in the great game for control of space.

But the final battle will be fought in the reddish sands of a backwater world, and the prize will be the staggering secret that has lain hidden in a remote cave for untold centuries.

All the Powers struggle for the ultimate victory, but at what cost?

The Third Frontier War is over, and the Western Alliance is triumphant. All across human-occupied space, colony worlds celebrate the coming of peace.

But peace is an elusive dream, and more trouble is brewing. The war was expensive, and the economies of the Superpowers, always fragile, are on the verge of total collapse.

The Directorate, the shadowy intelligence organization that has become the true power behind the Alliance government, plans to strip the colonies bare to pay the costs of war. Already, they are tightening their control over the freewheeling colonial governments. And the Marine Corps faces total destruction at the hands of the worst traitor in its history.

But the colonists are a different breed than the passive mob on Earth, and they have no intention of meekly surrendering their hard won freedoms. On worlds all across the frontier, plans are hatched and weapons hoarded. And in taverns and meeting halls the words of an ancient text are uttered in hushed tones. A little rebellion, now and then, is a good thing.

The Alliance and its colonies have called a truce and signed the Confederation Agreement, ending the rebellion and providing the frontier worlds with guarantees of limited self-government. It is a makeshift agreement, born of necessity and exhaustion. No one expects the deal to last, and both sides are preparing for the next showdown.

But from the depths of space another challenge is coming, one that will endanger the very survival of mankind and force not just the Alliance and its colonies, but all of the Superpowers, to join forces or face annihilation.

The dusty ruins the Alliance discovered on Epsilon Eridani IV were built by an ancient race, eons dead. But their guardians remain, and the disturbance of the long silent caves triggered an automated alert, one which has been heard. And answered.

Erik Cain and his Marines grimly take to the field once again, for what may be their final battle, against the robotic legions of the First Imperium. But facing a ruthless and technologically superior enemy may be easier than learning to fight alongside old enemies.

The robotic legions of the First Imperium burst into human space, destroying everything in their path. Their antimatter-powered fleets drove back the desperately defending human forces, seizing world after world. Directed by the maniacal Regent, the enemy pressed forward with one goal – the destruction of mankind.

The Superpowers of Earth, bitter enemies for over a century, have at last banded together to face the threat from outside. Their combined forces have fought stubborn delaying actions to buy time, but they haven’t managed to stop the relentless onslaught. Now the Rim has fallen, and the heart of human space lies before the invaders.

On three worlds, mankind will make its stand, and all the power Earth and its colonies can muster has been gathered there. Three worlds – Sandoval, Garrison, and Samvar. The Line.

Erik Cain grimly leads his veteran Marines and their new allies to Sandoval, to fight and to hold that world against anything the enemy throws at it. But Cain plans more than just a defense; he intends to annihilate the enemy forces…and he’ll sacrifice anything to win the ultimate victory. Even his soul.

The combined forces of humanity have beaten back the First Imperium invasion. For the first time, the enemy has been checked in battle. The cost was high in blood and suffering, but the Line held. The heart of human-occupied space has been saved from annihilation. For now.

There is little time for the victorious warriors to savor their triumph or mourn their dead. The First Imperium has been driven back, but it has not been defeated. No one expects the fruits of victory to be more than a brief respite.

Augustus Garret, Erik Cain, and the rest of the human high command have a decision to make. Do they stand on the defensive, waiting for the massive second invasion they all know will come? Or do they consider another option, one that compels them to face overwhelming odds, and launch a strike that could end the war in one campaign?

The attack ship Hornet returned home after a miraculous run through enemy space, and her crew brought with them priceless intelligence…the location of a world of the First Imperium. In the capitals of Earth, the ruling classes call for caution, for the armed forces to stand on the defensive. But on the frontier, Garret and his compatriots are planning something different, and they do not intend to be deterred. They are going to take the war to the enemy. They are going to march into hell’s heart.

The war with the First Imperium is over, and Grand Fleet is limping home from the frontier. Erik Cain, Augustus Garret, and the rest of the high command are grimly satisfied that humanity has been saved from the First Imperium menace. There is no joy, however…no elation at the “victory.” The losses this time were too heavy…too personal…to bear. They did what had to be done to drive back the enemy and save the human worlds from certain destruction. Now they were left to find a way to live with the gut wrenching decisions that victory had required.

Augustus Garret needed time. Time for repairs, time to replace losses, time to learn how to go on in the aftermath of what he’d done. But the fleet wasn’t heading for a well-deserved rest…they were moving into another firestorm. A new menace, one as deadly as the First Imperium, was waiting for them, and it threatened to shatter the fragile alliance of the Earth powers and throw all of human space into another desperate war…one that might be the final confrontation.

On world after world, mysterious forces are invading, taking control of the most vital colonies. The invaders are well-drilled powered infantry, veteran forces that quickly shattered the planetary militias and established brutal occupation regimes.

Garret, Cain, and the leaders of the Alliance’s forces must rally themselves once again to face this new threat…an unknown enemy that is as well trained, experienced, and equipped as the Marines themselves. Indeed, on some colony worlds rumors are already spreading that the invaders are the Marines themselves, that they have come to conquer, to rule…

Gavin Stark, the former head of Alliance Intelligence, and the bitter nemesis of the Marine Corps, has made his bid for power. The manufactured clone soldiers of his Shadow Legions have seized control of dozens of colony worlds, imposing his brutal rule over millions of colonists. His plan is no less than to subjugate all mankind under his iron fist.

On Earth, Stark’s manipulations have brought the Superpowers to the brink of war, threatening the Treaty of Paris and its prohibition against terrestrial warfare. For a century, man had restricted his conflicts to space, but now the Powers are sliding closer to the brink…the final battle that could kill billions, and turn Earth into a wasteland.

On a few key colony worlds, Erik Cain, Elias Holm, and the remnants of the shattered Marine Corps struggle against Stark’s vast armies…the only hope of turning back the tide of destruction and despair that threatens to engulf all mankind. They are outnumbered and outgunned, but they will fight nevertheless, standing grimly in the breach, holding back Stark and his dark legions.

The Marines will give their all, fight with the last of their strength and resolve. But this time the cost will be too high to bear, too personal. Even Marines need their heroes, their legends. But even legends die.

Erik Cain is the hero of the Marine Corps, a celebrated warrior who has led his grim veterans into every war the Alliance and mankind have faced. But now he has left the Corps, driven to near madness by an overwhelming need for vengeance. He has sworn to kill Gavin Stark, the madman responsible for his mentor’s death and, with a small band of dedicated followers, he is pursuing his prey across occupied space.

Meanwhile, on a dozen colony worlds, Marines land to face the occupying forces of Stark’s Shadow Legions. They are supported by the Janissaries, their longtime enemies, now turned allies, but they are exhausted and outnumbered, facing a vastly superior enemy entrenched and waiting for them. But they are veterans, Marines and Janissaries both, men and women who have battled the armies of the First Imperium and lived to tell the tale. They know what is at stake, and they are determined to prevail, even if none of them come back.

And on Earth, the economic collapse Stark engineered has shattered the Treaty of Paris and its century-long prohibition against terrestrial warfare. Millions are already dead as the war between the Superpowers spreads across the Earth, a growing conflagration that could end in apocalyptic nuclear, chemical, and biological exchanges between the powers.

Will mankind live under the iron boot of Gavin Stark and his clone descendants forever? Or will Erik Cain and the Marines defeat him once and for all?