Leviathan Falls - Book 9 of the Expanse (now a Prime Original series)

The biggest SF series of the decade comes to an incredible conclusion in the ninth and final novel in James S. A. Corey's Hugo Award-winning Expanse series. NOW A MAJOR TV SERIES FROM AMAZON PRIMEHUGO AWARD WINNER FOR BEST SERIES'Interplanetary adventure the way it ought to be written' George R. R. MartinThe Laconian Empire has fallen, setting the thirteen hundred solar systems free from the rule of Winston Duarte.
But the ancient enemy that killed the gate builders is awake, and the war against our universe has begun again. In the dead system of Adro, Elvi Okoye leads a desperate scientific mission to understand what the gate builders were and what destroyed them, even if it means compromising herself and the half-alien children who bear the weight of her investigation. Through the wide-flung systems of humanity, Colonel Aliana Tanaka hunts for Duarte's missing daughter.