Allegedly kidnapped from a secret city in Central America, the “Aztec children” began a showman’s career in the early-1850s. They died around 1900, after being observed by countless pathologists and ethnologists from Europe and the US. Most of the literature on the “Aztec children” has emphasized racial theories, the imperial gaze, and the character of “ethnological shows”, where monstrosity and ethnicity were practically synonymous. Less attention has been paid to the fact that scientists continuously insisted that the case was false, an argument that instead of debunking the myth of the “Aztec children”, contributed to establishing the “Aztecs” as “a matter of fact”. In examining the case of the “Aztec children”, this essay aims to explore what can be called the shifting nature or elusiveness of falsehood.