At age seventy-five, John Perry enlists in the Colonial Defense Forces—who recruit only the elderly—and receives a new engineered combat body, discovering that humanity is engaged in a brutal and constant war for habitable planets across the galaxy. Fast-paced, funny, and emotionally smart, the novel is an affectionate engagement with Heinlein's military science fiction tradition that also grapples seriously with mortality, identity, and the cost of war. A massively entertaining debut.