Ever since the serendipitous discovery of planet Uranus in 1871, astronomers have been hunting for new worlds in the outer regions of our solar system. This exciting and ongoing quest culminated recently in the discovery of hundreds of ice dwarfs in the Kuiper belt, robbed Pluto from its 'planet' status, and led to a better understanding of the origin of the solar system. This timely book reads like a scientific 'who done it', going from the heights of discovery to the depths of disappointment in the hunt for 'Planet X'. Based on many personal interviews with astronomers, the well-known science writer Govert Schilling introduces the heroes in the race to be the first in finding another world, bigger than Pluto.