Canada must prepare for an isolationist and unpredictable neighbour to the South should a MAGA leader gain the White House in 2025. The American-led global order has been increasingly challenged by Chinese assertiveness and Russian revanchism. But while Canadians have been paying attention to the re-emergence of great power competition, they assume that Americans will continue to provide global leadership in the West. Canada Alone sketches a more dystopian future: we are likely to see the illiberal, anti-democratic, and authoritarian Make America Great Again movement regain power and dominate American politics in the 2020s. This will have profound foreign policy consequences: if a MAGA Republican--either Donald J. Trump himself or a Trumpian candidate--becomes president in 2025, the West will likely fracture under the twin stresses of a re-invigorated America First policy and the purposeful abandonment of American global leadership. This would leave Canadians, for the first time in their history, all alone in North America with an increasingly dysfunctional United States. Canada Alone outlines what Canadians will need to navigate this deeply unfamiliar post-American world.