Australia's Great Barrier Reef sits at the center of a fight over coal. This film follows environmentalists trying to stop a wave of port expansions along the Queensland coast, where new terminals and dredging projects are being built to ship coal out through waters that overlap the reef itself. Marine scientists and campaigners lay out what dredging spoil and increased tanker traffic do to coral and seagrass, while port authorities and mining interests make the economic case for expansion. UNESCO's threat to strip the reef of its World Heritage status hangs over the whole story, giving the environmentalists a deadline and a lever they use to pressure the Australian government. The film tracks the back and forth between conservation groups, coal companies, and regulators as approvals move forward even as warnings mount. It is a portrait of a specific, narrow window in which a decision either protects one of the world's largest coral systems or locks in decades of industrial shipping through it.