A British exploration team sets out to find caves beneath the Giza pyramid complex, working from stellar alignment calculations and a forgotten diary kept by the nineteenth-century excavator Henry Salt. The film follows their research and fieldwork, cutting between interviews with team members, dramatized readings from Salt's diary, and footage shot inside the cave system once it is located. It also tracks the fallout with Egyptian antiquities chief Dr. Zahi Hawass, who first denies the caves exist, then later leads a film crew through them himself for a reality television segment. That reversal becomes the film's real hook: a discovery that goes from dismissed to filmed for cameras within the same story. The caves, their possible age, and what they might have been used for remain open questions the team can only partly answer with the evidence on hand. Anyone curious about how a diary entry and some astronomy can reopen a site as picked-over as Giza will find the process laid out step by step.