Suddenly, my troubles seem easy...

Like clockwork each year, 100 million monarch butterflies set off on an incredible journey across North America, flying 2,000 miles to reach their remote destination: a tiny area high in the mountains of Mexico. How do the butterflies achieve this tremendous feat of endurance - and how, year after year, do the monarchs navigate with such hair's-breadth precision. NOVA flies along, visiting the spectacular locations the butterflies call home and meeting the dangers they encounter along the way...The Incredible Journey of the Butterflies...8PM