For two years, Karen Lips lived alone in a rainforest in Costa Rica to research a species of frog she had previously discovered there. In Miami, she wanted to write her dissertation, but soon realized that she was still missing some data. But when she returned, the frogs had disappeared. She could no longer find a single specimen. She soon realized that there are more cases around the world. At the same time and on different continents, thousands of miles apart, dozens of frog species had already disappeared. Something is sweeping through the forests and streams that they cannot withstand. Only what is it that is causing entire populations to disappear? And where does it come from?