Aubrey de Grey left a career in computer science to become a gerontologist, and this Channel 4 documentary follows his argument that aging is an engineering problem rather than an inevitability. De Grey lays out his case on camera: that the human body is a machine that accumulates specific kinds of molecular damage over time, and that repairing that damage systematically could extend life far beyond current limits, perhaps indefinitely. The film treats him as a serious but polarizing figure, someone dismissed by parts of the scientific establishment as a fringe theorist even as his ideas draw serious funding and attention. Interviews and his own extended explanations carry most of the film, walking through what a world without biological aging might actually look like and what it would take to get there. There is no reenactment or field footage to speak of; the interest here is entirely in one scientist's argument and how far he is willing to take it.