In the first part of the film, the astonishing life cycle of the monarch butterfly is depicted through captivating visuals and intricate details. Viewers are taken on a journey through the transformation of the delicate creature from an egg to a caterpillar, then into a chrysalis, and finally, the emergence of the iconic orange and black winged butterfly. Simultaneously, the story delves into the monarch's epic migration across North America, an arduous trek that covers thousands of miles, from Canada to the mountainous forests of Mexico—a natural phenomenon that bewilders and intrigues scientists and nature lovers alike.

Parallel to the marvel of the monarchs' journey, the film follows the passionate quest of Dr. Fred Urquhart, a Canadian zoologist obsessed with unlocking the secrets of the butterfly's migration. Along with his wife Norah, Urquhart embarks on a 40-year-long scientific investigation that becomes a lifelong mission. Their relentless pursuit for knowledge leads them to recruit an army of citizen scientists across North America to tag thousands of butterflies. This pioneering research aims to track the migratory patterns and finally reveal the mysterious destination of these enigmatic creatures. As the investigation progresses, the couple faces numerous challenges and the overwhelming task of mapping one of nature's most intricate and least understood migration rituals.