John Scalzi - Szellemhadtest (2019)

Humanity is threatened by a never-before-seen threat, three intelligent species are teaming up against its space colonies. Three races and one man. Humanity's only hope is that the traitorous scientist left behind a backup copy of his mind during his desertion. But no one knows how to use it. The Ghost Corps of the Colonial Defense Force has never been known for its moral qualms, so it tries to implant the cloned soul into a clone trooper... after all, the war is theirs to prevent, and they're willing to do anything for that purpose.

Scalzi picks up the fast-paced military sci-fi where War of the Elders left off, with an even more compelling story and upping the stakes. Rejuvenated elders and rapidly aging youth fight a special war that is exactly like all wars in history: infinitely dirty. The only refuge is to find the moral compass within oneself, as Scalzi's protagonist with an adventurous fate managed to do. But will this be enough even now, in this all-consuming war?