What is it about eels? Depending on who you ask, they are a pest, a fascination, a threat, a pot of gold. What they are not is predictable. Eels emerged some 200 million years ago, weathered mass extinctions and continental shifts, and were once among the world’s most abundant freshwater fish. But since the 1970s, their numbers have plummeted. Because eels—as unagi—are another thing: delicious. Ellen Ruppel Shell travels in the world of “eel people,” pursuing a burgeoning fascination with this mysterious and highly coveted creature. This is an enthralling, globe-spanning look at an animal that you may never come to love, but which will never fail to astonish you, a miraculous creature that tells more about us than we can ever know about it.