Continuing the deep-space adventures of Admiral John "Black Jack" Geary and company (Beyond the Frontier: Dreadnaught, 2011, etc.).
Having defeated—or at least fought to a standstill—the alien "enigmas" in the previous book, Geary has taken his battered fleet through hyperspace only to run headlong into a second hostile alien race. While attempting to unravel the politics behind the Alliance's orders that has brought him here, Geary must contend with a race that numbers in the tens of billions; worse, they have super-battleships vastly larger than anything he can bring to bear—and they have technology that can divert kinetic energy weapons. Another big problem for Geary and his captains is that their ships were built only for a limited operational lifetime, and that limit is rapidly being reached, with equipment failure an ever-present danger. Still waiting in the wings: a third star-faring alien race. Even if Geary can find some way to cope, the fleet is still a long way from home, with both the enigmas and the remnants of the Syndics between them and their destination. And when—if—they do get home, Geary isn't sure he can trust anyone in the Alliance. Campbell describes the battles—and there are plenty of them—clearly and precisely, but conveys no visceral sense of what it feels like to be in one. The tension racks up with never a hint that Geary feels it or that the good guys might actually lose. And along with some memorably intriguing aliens, the human characters are plentiful rather than highly developed. We're offered little hint of how any of this advanced technology might actually work. Maybe you have to read all the previous books.
Absorbing rather than gripping, although neither series addicts nor newcomers will be disappointed.