Bill McKibben builds his campaign against the fossil fuel industry around a single number: the world's proven coal, gas, and oil reserves contain roughly five times the carbon that can be burned without pushing the planet past catastrophic warming. The film follows McKibben and the 350.org movement he leads as they turn that math into a strategy, staging protests against the Keystone XL Pipeline and pressing universities, cities, and pension funds to divest their holdings in fossil fuel companies. Rallies, campus meetings, and organizing sessions show the mechanics of building a national campaign from scratch, while McKibben makes the case, on stage and in interviews, that climate change is a moral fight as much as a scientific one. The film treats Big Oil, Big Coal, and Big Gas as the opposition to be confronted directly rather than negotiated with, and tracks how the divestment tactic, borrowed from the anti-apartheid movement, spreads from individual campuses toward institutional endowments. It ends with the movement still underway, its outcome unresolved.