French architect Jean-Pierre Houdin lays out his theory for how the Great Pyramid of Giza was actually built, arguing against the old picture of armies hauling stone up a straight external ramp. His case rests on an internal spiral ramp, tunneled through the pyramid's body as it rose, that let workers drag blocks upward inside the structure rather than around it. The film moves chapter by chapter through his argument, from what he calls the pyramid's two central enigmas to the specifics of construction in its later years, before turning to burial chambers and the sealing of the tomb, a process he describes taking seventy days. Aerial views of the Giza plateau frame the scale of the project: millions of limestone blocks, decades of labor, and a monument still standing four and a half thousand years later. Houdin walks through diagrams and models rather than reenactments, treating the pyramid as an engineering problem to be solved rather than a mystery to be marveled at.