A former ocean scientist goes in pursuit of the slippery story of jellyfish, rediscovering her passion for marine science and the sea's imperiled ecosystems.

More than a decade ago, Juli Berwald left a career in ocean science to raise a family in landlocked Austin, Texas, but jellyfish drew her back to the sea. Recent, massive blooms of billions of jellyfish have clogged power plants, decimated fisheries, and caused millions of dollars of damage. Driven by questions about how overfishing, coastal development, and climate change were contributing to a jellyfish population explosion, Juli embarked on a scientific odyssey. She traveled the globe to meet the biologists who devote their careers to jellies, hitched rides on Japanese fishing boats to see giant jellyfish in the wild, raised jellyfish in her dining room, and throughout it all marveled at the complexity of these alluring and ominous biological wonders.