Eighty conditions. One explanation. Your body is attacking itself, and nobody knows why. For seventy years that sentence has closed the conversation for millions of people diagnosed with multiple sclerosis, lupus, rheumatoid arthritis, Hashimoto's, Type 1 diabetes, Crohn's, psoriasis and dozens more. It sends them home with a prescription they are expected to take for life. It rarely sends anyone looking for a cause. No Autoimmunity goes looking. It starts with the label for Humira, once the best-selling drug in the world, which lists new autoimmune disease among its own risks. It traces the autoimmune category back to rabbit experiments in 1956, where the "self-attack" was produced with a needle. Along the way it recovers Charles Richet's 1913 Nobel warning about injected foreign proteins, and Evelyn Hess's catalog of more than seventy medications that produce lupus-like disease which clears when the drug is stopped. Then it works through the body system by system, from nerves and glands to gut, skin, joints and blood, and documents the people who recovered once the source of injury was removed: mercury fillings taken out, implants explanted, diets changed, drugs withdrawn. Every chapter closes with a plain-language explanation a six-year-old could follow, because the argument is simpler than the framework has made it sound. The body does not attack itself. It responds to what has been done to it. Every claim is referenced. Every source is verifiable.