The search for the 'missing link' begins in the mid-nineteenth century, when scientists first went looking for fossil proof of a half-ape, half-human ancestor that would explain where people came from. This film traces that century and a half of digging, arguing, and revising, populated by fanatics chasing bone fragments, frauds who faked what they could not find, amateurs who stumbled onto real discoveries, and professionals who spent careers being proven wrong. Reenactments put faces on the scientists at the moment of discovery, then jump back hundreds of thousands and sometimes millions of years to show how the human and near-human ancestors they were digging up actually might have lived day to day. Interviews with working scientists fill in what the fossil record can and cannot prove, and how the very definition of a 'missing link' kept shifting as new finds forced old theories out. The real story here is less about the fossils than about the messy, human process of building a science out of scraps.