Five years ago, Mira Bunting founded a guerrilla gardening group: Birnam Wood. An undeclared, unregulated, sometimes-criminal, sometimes-philanthropic gathering of friends, this activist collective plants crops wherever no one will notice. Then Mira stumbles on an answer, a way to finally set the group up for the long term: a landslide has closed the Korowai Pass, cutting off the town of Thorndike.