A vet and an assistant arrive at Klaus Hoffmann's backyard chicken coop with a portable laboratory, checking his 40 birds for age, weight and viral load, then comparing the results against health data from Hoffmann himself and his dog. The scene is part of a growing research push into 'zoonoses,' infections that jump from animals to humans, the likely origin of the coronavirus pandemic. Fabian Leendertz of the University of Greifswald, who worked with the WHO to trace COVID-19's origins, explains his field of 'One Health,' which studies how humans, animals and the environment interact to spread new viruses. The film follows researchers trying to catch the next dangerous pathogen before it spreads, moving between farms, labs and interviews with scientists tracking disease at the animal-human border. Rather than dwelling on past pandemics, the documentary treats surveillance itself as the story: sampling chickens, testing wildlife, and building early-warning systems meant to buy the world time before the next outbreak becomes a headline.