Bees are in serious danger. Populations of honey bees are dying at levels that are unprecedented. Close to half of the bee colonies in the United States die off every single year. Thousands of semi-trailers crisscross the country in the dead of night delivering goods through the darkness to stores, warehouses and factories nationwide. But some of them carry highly unusual cargo. Honey bees. Tens of billions of them are transported back and forth from one end of the United States to the other in a unique annual migration that's indispensable to the feeding of America. One out of every three bites we eat, the growth of almost all our fruits, nuts and vegetables, would be impossible without pollination from bees. Director Peter Nelson talks to farmers, scientists, chefs, and academics along the way to give a broad perspective about the threats to honey bees, what it means to our food security and how we can improve it.