From USA Today best-seller Robert Armstrong comes the fast-paced sci-fi series Echo Effect. Get the first two titles from the series in this audiobook: Echo Effect and Symphony of Descension.

The world’s food supply grows aggressively, occupying every inch of earth, no matter how inhospitable. World hunger is averted. Humanity flourishes. RC-714 is digested, absorbed…and passed on. The Change affects small fast-breeding mammals first. They multiply with the same aggressive speed as the ExoGen plants, but an insatiable hunger drives them to violence. A war between species breaks out. When RC-714 reaches humanity, along with every other large creature on the planet, civilization implodes.

Two centuries after the Confederation staved off an invasion by the robotic Locusts, Captain Jack Romanoff faces mandatory retirement from an ever-shrinking navy. Actions speak louder than words. The Confederation doesn’t think the Locusts are coming back. But what if the politicians are wrong?

The Ember War, book 1: The Earth is doomed. Humanity has a chance. In the near future, an alien probe arrives on Earth with a pivotal mission: to determine if humanity has what it takes to survive the impending invasion by a merciless armada. The probe discovers Marc Ibarra, a young inventor who holds the key to a daring gambit that could save a fraction of Earth's population. Humanity's only chance lies with Ibarra's ability to keep a terrible secret and engineer the planet down the narrow path to survival.

A company of Army Rangers is sent on an interstellar colony ship to secure a foothold on a dangerous, alien planet through violence of action. Leaving behind a warring Earth flung headfirst into a conflict of mutual assured destruction, the Rangers and the accompanying crew of first colonists are guided on a 40-year journey by an unprecedented artificial intelligence. But when they emerge from the frigid embrace of cryosleep, they awake to a nightmare, finding themselves greeted by the same ruthless enemy that brought about the ruin of Earth.

When the Earth Republic is savagely attacked, they recruit the universe’s most dangerous minds to retrieve their stolen warships. But as this ragtag group of criminals embarks on a suicide mission to fight for their lives and freedom, an even bigger threat emerges….

Logan Conner is the son of a king, the heir to the largest of the five star-dominions, and the best mech pilot in the galaxy. His people are plagued by pirates and raiders, surrounded by enemies, and not even his father can fight them all. Logan gives up his position, his rank, even his name, and becomes Jonathan Slaughter, leader of a rough-and-ready band of mercenary mech-jocks bent on taking the battle to the enemy on their own terms.

Space travel just isn't what it used to be. With the invention of quantum teleportation, space heroes aren't needed anymore. When one particularly unlucky ex-adventurer masquerades as famous pilot and hate figure Jacques McKeown, he's sucked into an ever-deepening corporate and political intrigue. Between space pirates, adorable deadly creatures, and a missing fortune in royalties, saving the universe was never this difficult!

Five years ago, the US Space Force became a reality. And while those writing the checks took things very seriously, the other military branches did not. As a result, Space Force was populated by undesirables. My name is Captain Ethan Stone, a decorated member of SEAL Team Six turned Space Force "recruit". Flash forward five years and between tenses. President West is in office. Power has shifted. And Space Force is defunded. With just a handful of us still living on base, we find ourselves being evicted. But before all of us can leave, aliens invade.

After decades hunting wanted offworlders throughout the solar system, Corporate Bounty Hunter Malcolm Graves doesn't bother asking questions. So long as the pay is right, he's the man for the job. And he always works alone. But when a high-profile bombing on Earth has Pervenio Corp clamoring for answers, they force him to team up with a strange, cyber-augmented partner. A young man more interested in statistics than instinct. Their assignment: Track down a suspected group of extremists from Titan who will go to any length to free their moon from the grip of Earth's corporations.

Ataegina was an isolated world of medieval castles, varied cultures, and conquests, vibrant until the demons rose and spread relentless destruction. Swarms of lethal creatures with black husks, murderous claws, barbed tails, and dreaded “tooth-tongues” raged through the lowlands, killing 90 percent of the planet’s population. Terrified survivors fled to hidden mountain keeps where they eke out a meager existence. When a trio of young warriors discovers a new weapon, they see a chance to end this curse. To save humanity, they must fight.

Lauren Russell often wondered why her father had been so adamant about teaching her skills that most other fathers wouldn't even consider teaching their daughters. Ever since she was little, she had been taught how to live and survive outdoors, and how to use firearms to protect herself and those around her. Some of the training had been a bit extreme. Or had it been? Many of her questions were answered the day the world as she knew it ended.

With average grades, less than stellar play in baseball, and a single mother struggling to make ends meet, it looks as if Austin's only way to continue his education would be through some kind of miracle.

Former Marine Arthur Holland’s destiny begins when an aircraft crashes on his property in the mountains of Colorado. He moves to investigate and to help any survivors, but the closer he gets the less control he has of his movements. An unknown force urges him to open the door of the mysterious craft, discovering the secret that lies within: a dead, alien pilot and a peculiar, otherworldly crystal. If that wasn’t enough, the crystal feels like it is alive. That’s when he hears a single word inside his mind: run.

The year is 2650. Seventy-five years ago, an alien fleet attacked Earth. Without warning. Without mercy. We were not prepared. Hundreds of millions perished. Dozens of cities burned. We nearly lost everything. Then the aliens abruptly left. We rebuilt. We armed ourselves. We swore: never again. But the aliens never came back. Until now. With overwhelming force the aliens have returned, striking deep into our territory, sending Earth into a panic.

They tried to destroy our planets. Our way of life. They tried to send us into extinction. But we, the Coalition, fought them and won. That was a decade ago. They’re known as the Host: a cabal of aliens seeking to dominate our sector of space. And they’re back - with help from a powerful new enemy. We’re outnumbered and unprepared. But there is hope. An ancient race of long-dead but technologically advanced aliens called the Navigators have a ship called the Blackstar that could potentially turn the tide. That is if I, Kai Locke, a humble ship racer, can find it and learn how to harness its power in time.

Former Marine Arthur Holland’s destiny begins when an aircraft crashes on his property in the mountains of Colorado. He moves to investigate and to help any survivors, but the closer he gets the less control he has of his movements. An unknown force urges him to open the door of the mysterious craft, discovering the secret that lies within: a dead, alien pilot and a peculiar, otherworldly crystal. If that wasn’t enough, the crystal feels like it is alive. That’s when he hears a single word inside his mind: run.

The year is 2650. Seventy-five years ago, an alien fleet attacked Earth. Without warning. Without mercy. We were not prepared. Hundreds of millions perished. Dozens of cities burned. We nearly lost everything. Then the aliens abruptly left. We rebuilt. We armed ourselves. We swore: never again. But the aliens never came back. Until now. With overwhelming force the aliens have returned, striking deep into our territory, sending Earth into a panic.

Before he was Oldtimer, he was Craig Emilson, a young doctor,sucked into military service at the outbreak of World War III. Enlisting to become a Special Forces suborbital paratrooper, Craig is selected to take part in the most important mission in American military history, a sortie into enemy territory to eliminate the world's first strong artificial intelligence.

Evan Gabriel wasn't always a feared and respected North American Federation Navy Commander. Before dangerous missions to the ice-bound planet of Poliahu, the deadly jungle world of Eden, and politically corrupt Mars, he was a simple recruit, fighting to make his mark in the elite Naval Special Forces…and was part of a top-secret military experiment that would change his life forever. Zero Point tells the tale of a young man faced with difficult choices and dangerous trials.

When humanity reaches for the stars, our probes are destroyed. They crash into an incredibly advanced piece of technology: a massive force-field. Unknown beings have placed a barrier around our star and planets, enclosing us within. We’re locked inside a Great Sphere. Was this invisible obstacle built to imprison us - or to protect us? No one knows the truth, but it soon becomes clear the barrier has leaks. Aliens infiltrate and try to sabotage our efforts to escape our cage.

Darius Drake is desperate to save his daughter, Cassandra. So desperate he's willing to risk their lives in cryo-sleep to give her a future. But the dark, freezing vault where he wakes up is nothing like the luxurious Florida hospital he remembers. Everything about this place is alien to him, even the language. Little does he know how alien it really is. Darius and his daughter go exploring their new surroundings with a few others from the cryo pods, and they soon discover frozen, mutilated bodies everywhere.

After decades hunting wanted offworlders throughout the solar system, Corporate Bounty Hunter Malcolm Graves doesn't bother asking questions. So long as the pay is right, he's the man for the job. And he always works alone. But when a high-profile bombing on Earth has Pervenio Corp clamoring for answers, they force him to team up with a strange, cyber-augmented partner. A young man more interested in statistics than instinct. Their assignment: Track down a suspected group of extremists from Titan who will go to any length to free their moon from the grip of Earth's corporations.

The Earth lies in ruins in the aftermath of an extraterrestrial invasion, the land devastated by a desperate war with no winners between mankind and a race of vicious, intelligent creatures. The seas are drying up while the atmosphere corrodes and slowly cooks any life remaining on the now desolate rock. Food is scarce, trust even more so, and the only people left alive all have done horrific things to stay that way.

The year is AD 2790. With space elevators and giant orbital fleets hovering over Earth, open war looks inevitable, and people are anxious to get away. The lines are drawn, with the Confederacy in the East and the First World Alliance in the West. In hopes of finding a refuge from the looming war, the Alliance is sending Captain Alexander de Leon to explore an Earth-type planet, code-named Wonderland, but at the last minute before launch, a Confederate fleet leaves orbit on a trajectory that threatens both the mission and Alliance sovereignty.

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 Tantalus 13 survey expedition went off the rails as soon as Mary Ketch and the crew of the Diamelen learned that the thing beneath their feet wasn’t a planet. An impossibly vast and ancient artificial structure lies below, hidden from the universe under a façade of cratered stone. SCARAB arrived on Tantalus 13 two years ago. An artificially intelligent, self-constructing factory, it was supposed to aid the crew in their mission, to meet their every need.

The Earth died when aliens rained thermonuclear warheads on her cities and sprayed the surface with a bio-terminator. A deadly poison drifted to every corner of the planet, threatening the last survivors with annihilation. For a soldier like Creed, there is only one way to keep breathing untainted air. He must bury his hatred of the extraterrestrials and join the Jelk Corporation as an assault trooper, leaving the planet for outer space. In return for his and other people's services, the corporation will house the last humans for as long as the assault troopers keep winning.

Archaeologists Pippa Quinn and Charlie Jackson find advanced technology in undisturbed 16th-century graves. A portent, the discovery precedes thousands of giant sinkholes opening up across the globe as extreme weather threatens the population. Charlie suspects the two are related.

In the final days of the empire, Cyborg Corps Colonel Leonidas Adler plans to die in a manner befitting of an imperial officer. He will fight until his last breath, giving his life to defend Emperor Markus, as it was meant to be. But when the emperor himself summons him for a final special mission, how can he refuse?