Old-growth trees can stand for centuries, and this DW film argues they are irreplaceable for biodiversity and carbon storage even as logging, drought, and pests thin their numbers worldwide. Biologist Meg Lowman, now 70 and the first scientist to study forest canopies in the 1970s using self-built hoists, leads the film into the Peruvian Amazon, where she and a group of ecotourists walk canopy walkways built and maintained by local residents who also work as guides. Lowman's goal is to protect ten of the world's most biodiverse forests this way. In Germany, where no forest meets the classic definition of primeval, the startup woodify leases woodland and contracts landowners to leave it entirely unmanaged for 30 years, letting fallen trees rot in place. The company sells certificates for the extra CO2 the wild forest sequesters, based on calculations from the Eberswalde University for Sustainable Development. The film moves between ecotourism in the Amazon and a carbon-market experiment in central Europe, treating both as bets on letting forests age undisturbed.