The Ghost Fleet4 books in series
Cascade Point Summary
Grant Stone and his crew just want to be left alone. They fly at the edges of Alliance space, surveying new systems far from the problems that brought them all together. Some are former military, while others have more colorful pasts. Everyone aboard the Fallen Angel has a reason for staying on the fringes. It's a good life, but a chance discovery will change everything.
Confronted by an enemy powerful enough to threaten all of human civilization, Grant and his crew are forced to choose between confinement or joining the Ghost Fleet, a hidden network of ships recruited and run by the Alliance Navy. Faced with an existential danger, Grant will lead his team into the far reaches of unknown space to keep the brewing conflict from exploding into all-out war.