A look inside the often hidden world of parasites turns the clock back to the beginning of life on Earth to answer key questions about these highly evolved and resilient life forms.

Prologue: a vein is a river -- 1. Nature's criminals -- 2. Terra incognita -- 3. Thirty Years' War -- 4. Precise horror -- 5. Great step inward -- 6. Evolution from within -- 7. Two-legged host -- 8. How to live in a parasitic world -- Epilogue.