The strange landscape of pits and mounds known as Grimes Graves near Thetford in Norfolk, England, is the site of one of Britain's earliest industries, flint mining, and its associated craft of flint knapping. This industry was carried on in the area within living memory - the craft survived long enough to be filmed in the 1940s and historic footage of this is included. Next, the mines are investigated and examined for evidence of how neolithic miners extracted the flint - the pits are the filled-in entrances to mine shafts. A school party is shown beginning their investigation of the mines. A professional flint knapper, John Lord, takes the viewer on a tour of the mines, including one of the deepest that is not open to the public. The flint is found underground embedded in the chalk, and the best is at the bottom of the pit, 60 feet down. Here tunnels lead off the central chamber into a maze of galleries beyond. John Lord demonstrates how the neolithic miners must have worked, using antler picks, by scraping away the chalk to loosen the large flint boulders. In the last part of the video he demonstrates the skills needed to make an axe head by using a pebble to split the flintstone and shape it. Finally the cutting edge of the axe head is put on, using an antler to flake off smaller pieces.