It's a natural history epic. It's a compelling detective story. It's a scientific adventure at its best. It took Dr Fred Urquhart almost 40 years to discover the monarch butterflies' secret hideaway and prove the most incredible migration on Earth. Following the year-long annual migration cycle of the butterflies, the award-winning production team filmed hundreds of millions of monarchs in their remote overwintering sanctuaries in Mexico in 2011 and again in 2012 and also along their migratory routes from Canada, across the U.S. and into Mexico. The film immerses you in the astounding migration experience as two generations of the butterflies migrate north and then a Super Generation miraculously finds its way from Canada to a few isolated mountaintops in Mexico.