Monarch butterflies abound in Canada. We marvel at their beauty and the magic of their metamorphosis. Familiar as they are to us, these tiny creatures nevertheless harbour many secrets. Perhaps the deepest mystery is the monarchs' annual migration. Each autumn, they travel unimaginably long distances, something no other butterflies do. How do they know when to migrate? How, unguided by memory, do they navigate to their destination in the heart of the threatened Mexican jungle? Sue Halpern recounts the mesmerizing story of these mysteries, and the race to solve them. She describes the discoveries of Canadian biologist Fred Urquhart and his wife, who first encouraged amateur lepidopterists to tag butterflies. We follow her to Mexico, where she searches for butterflies. She introduces us to Don Davis, an enthusiast who has tagged an estimated 20,000 monarchs since 1985. And though terrified of flying, she takes us on a flight with University of Toronto biologist David Gibo, as they attempt to predict the flight vectors of butterflies. Astonishing, fascinating, Four Wings and a Prayer, like our encounters with these delicate winged creatures, is a rare gem.