In 1941, on the eve of World War II, the buried dark history of the earth is exposed as powerful nations compete for ancient bones with the potential to shift the balance of power. Juzo, a former elite spy from the Nakano Army School who has fallen from grace and now spends his days addicted to opium, is approached by a masked man who reveals himself to be Dante, a bipedal dinosaur who has survived into the 20th century. Dante is an Oviraptor, part of a hidden lineage of upright-walking dinosaurs that have secretly coexisted with humanity, operating through clandestine organizations that have shaped world events from the shadows. Juzo and Dante form an unlikely cross-species partnership, drawn into a shadow war between rival dinosaur secret societies. On one side is the Knights in the Shell, a cabal that seeks to orchestrate humanity's self-destruction through perpetual warfare. On the other is the Castle of If, a resistance network that aims to prevent this extinction. Juzo and Dante become agents of the Castle of If, operating in the murky world of espionage that runs beneath the surface of global politics. Their central objective revolves around the Peking Man fossil, a missing piece of humanity's evolutionary past that holds deeper significance in the struggle between species. As they follow leads across China, Europe, and the Middle East, Juzo and Dante confront a succession of escalating threats: hidden laboratories working on nuclear fusion weapons that dinosaurs first gifted to humanity as fire, biological weapons reminiscent of the Black Death, and a shadowy figure named Chen Long who seeks to incite a dinosaur uprising. The partnership forces both Juzo and Dante to question where true allegiance lies, as Dante is both a potential savior and a potential enemy of humankind. Later arcs see the pair infiltrating deep into enemy territory to stop a doomsday weapon, and ultimately being dispatched to China on a mission to protect the communist leader Ho Chi Minh from a relentless assassin named Costello. When Juzo and Dante learn of future plans to assassinate both Mao Zedong and Ho Chi Minh, they are forced into an impossible moral choice that tests the limits of their bond across species lines. Throughout, the narrative weaves real historical figures and events into a world where the struggle between dinosaurs and primates secretly drives the wars and discoveries of the 20th century.