For more than a century, we have relied on chemical cures to keep our bodies free from disease and our farms free from bugs and weeds. We rarely consider human and agricultural health together, but both are based on the same ecology, and both are being threatened by organisms that have evolved to resist our antibiotics and pesticides. Patients suffer from C.diff, a painful, potentially lethal gut infection associated with multiple rounds of antibiotics; orange groves rot from insect- borne bacteria; and the blight responsible for the Irish potato famine outmanoeuvres fungicides. Chemical warfare is failing us. Fortunately, scientists are finding new solutions that work with, rather than against, nature. Emily Monosson explores science's most innovative strategies, from high-tech gene editing to the ancient practice of faecal transplants. There are viruses that infect and bust apart bacteria; vaccines engineered to better provoke our natural defences; and insect pheromones that throw crop-destroying moths into a misguided sexual frenzy.Some technologies will ultimately fizzle; others may hold the key to abundant food and unprecedented health. Each represents a growing understanding of how to employ ecology for our own protection. Monosson gives readers a peek into the fascinating and hopeful world of natural defences. Her book is full of optimism, not simply for particular cures, but for a sustainable approach to human welfare that will benefit generations to come.