A secret and deadly power lies hidden beneath the ground of Belgiums Flanders Field, one of the bloodiest battlefields of World War I.
Unexploded artillery shells are surfacing there more than 80 years after they were fired. Still unexploded, many are capable of killing. Some 3,000 shells are unearthed each year by farmers and construction workers, while others simply work their way up through the soil. The problem is immense: dozens of full-time workers cannot keep up with it. Even worse, thousands of these projectiles contain poison gas.