A novel set in the Known Space series, by Larry Niven and Edward M. Lerner.? It is a sequel to their previous novels, Fleet of Worlds, Juggler of Worlds, and Destroyer of Worlds. It is set 70 years before Ringworld and also has a sequel on it's own, Fate of Worlds.
Fleeing the supernova chain reaction at the galactic core, the cowardly Puppeteers of the Fleet of Worlds have
-just barely-survived. They’ve stumbled from one crisis to the next: The rebellion of their human slaves. The relentless questing of the species of Known Space. The spectacular rise of the starfish-like Gw’oth?. The onslaught of the genocidal Pak.
Catastrophe looms again as past crises return---and converge. Who can possibly save the Fleet of Worlds from its greatest peril yet?
Louis Wu? Trapped in the Wunderland civil war, all he wants is to go home---but the only possible escape will plunge him into unknowable danger.
Ol’t’ro? The Gw’oth ensemble mind fled across the stars to establish a colony world free from tyranny. But some problems cannot be left behind, and other problems
-like the Fleet of Worlds itself-are racing straight at them.
Achilles? Despite past disgrace, the charismatic Puppeteer politician knows he is destined for greatness. He will do anything to seize power---and to take his revenge on everyone who ever stood in his way.
Nessus? The insane Puppeteer scout is out of ideas, out of resources, with only desperation left to guide him.
Their hopes and fears, dreams and ambitions are about to collide. And the winner takes . . . worlds.