Only 4% of the universe consists of the matter that makes up you, me, every star, every and planet. Over the past few decades, a handful of scientists have been battling to understand the rest: the strange "dark matter" and even stranger "dark energy". In exhilarating detail, Panek takes us on an intimate tour of the epic rivalries, the eureka moments, the blind alleys, and the great mysteries that are redefining science and reinventing the universe.