“Three hundred million orange monarch butterflies leave Canada every August and fly all the way to Mexico,” says London-based (via Mexico and Los Angeles) filmmaker Ali Alvarez. “It's the most beautiful natural phenomenon I've ever seen. Butterflies normally live two weeks, but this ‘super-generation’ lives two months and travels to Michoacán state in central Mexico, arriving in late October, just around the Day of the Dead. The Mexicans say they are the souls of your family, coming back to visit you each year.”

When Alvarez read the story of a New York policeman sighting butterflies as he sifted through wreckage in the weeks following 9/11, she had a hunch they would be monarchs. “It took a while to track down Amadeo Pulley [the policeman] and win his trust. He was like, 'I don't know anything about butterflies!' He saw two- or three-hundred orange monarchs as he was searching for bodies. Who knows why they stopped there, in a place so toxic.”

Their encounter is part of Muerte es Vida (Death is Life), a meditative documentary that tells the stories of people along the migration route who have witnessed the butterflies and have a connection with them. “The Mexican expression that inspired me is 'To die is to live,'” says Alvarez. “Whatever you believe about the butterflies, they represent the idea that we are all connected. You might die, but somewhere in the planet you live on.”