伊恩·切尼和科特·埃利斯，两个大学时的好朋友，为了弄清楚人们日常吃的食物究竟如何而来，他们跑到了美国中部，并亲自尝试种植农作物，在爱荷华州，他们开垦了自己的农场，并将玉米等食物销往市场，成为“玉米大亨”。

King Corn is a fun and crusading journey into the digestive tract of our fast food nation where one ultra-industrial, pesticide-laden, heavily-subsidized commodity dominates the food pyramid from top to bottom – corn. Fueled by curiosity and a dash of naiveté, two college buddies return to their ancestral home of Greene, Iowa to figure out how a modest kernel conquered America. With the help of some real farmers, oodles of fertilizer and government aide, and some genetically modified seeds, the friends manage to grow one acre of corn. Along the way, they unlock the hilarious absurdities and scary but hidden truths about America’s modern food system in this engrossing and eye-opening documentary.