Sea levels are rising in New England at some of the fastest rates in the world. On a quiet ribbon of saltmarsh in Rhode Island, septuagenarian Deirdre isn’t prepared to accept the loss of her beloved saltmarsh sparrow - the species is facing extinction before 2050 due to elevated high tides inundating nests and drowning fledgling birds. Leading a team of citizen scientists, Deirdre unravels the secret to finding delicate nests amid thick marsh grass, while they design and deploy a low-cost ‘ark’ to try to raise the sparrow nests to safety.