A deadly secret lurks within our kitchens, medicine cabinets and gardens. Scratch beneath the surface of a coffee bean, a red pepper flake or an apple seed, and we find a bevy of strange chemicals. We use these to greet our days (caffeine), titillate our tongues (capsaicin) and even kill our enemies (cyanide). Based on cutting-edge science in the fields of evolution, chemistry, and neuroscience, this is the first book to reveal the origins of plant and fungal toxins, the mechanisms animals have evolved to overcome them, and how a co-evolutionary arms race made its way into the human experience. This perpetual chemical war not only drove the diversification of life on Earth, but is also intimately tied to our own successes and failures as a species.