Understand the terror of the invisible minefields around the world, ready to explode at any time. In fully one-third of a the world's countries, a misstep can mean a lost leg or life- from a land mine planted during war of on-going conflict. NOVA investigates the effects of minefields and the battle against this cruel weapon in one of the worst-affected regions, Cambodia, where there are as many land mines as people. Exclusive visits with the secretive Khmer Rouge highlight the frightening aspects of this epidemic. It's a world-wide problem, with an estimated 100 million land mines waiting to explode in 62 countries. Efforts by international leaders to solve this growing epidemic have been unheeded, in part because these mines have proven such an inexpensive and effective way to gain advantage during war. The solution: to painstakingly remove the mines, is expensive and dangerous.