With sea-levels rising, and the land deforested, over-mined, and affected by bushfires and drought—Tasmania is increasingly marooned, its people abandoned.

Nyx's father wants them to leave while they still can, but for Nyx, West Hobart is all she's ever known and where her mother is buried. She seeks solace in the single surviving tree near her home—an 80-foot pine that has defied all odds. Bea, too, finds solace in the tree, and facing a move to the mainland herself, leaves a despairing note, wedged into a hole in its trunk. Nyx finds the note and writes back. But Nyx and Bea don't realize how special their tree truly is . . .