Yellowstone is dying.New troubles are stacking up like cordwood for Chief Ranger Glenn Merrill, as Yellowstone’s existence is threatened by earth tremors and an imminent super-volcano. After a series of gruesome deaths claiming animals, tourists, and a ranger, it’s clear that something’s gone terribly wrong at the nation's oldest national park.But putting an end to these mysterious deaths is more than just the chief ranger’s job — it may be his end.Obsidian Tears plunges Glenn, his Shoshone friend, an aggressive young seismologist and an Arapaho healer into a world of Indian mysticism. Will man and nature join forces, or risk losing all of humanity to an ancient evil?