This Halcyon Classics book is Donald A. Wollheim's science fiction thriller The SECRET OF THE NINTH PLANET. On the day that the theft of the solar system's light begins, Burl Denning is with an archaeological expedition in the Andes, only a few miles from the source of the disturbance. Within hours the United States Air Force has ordered the expedition to investigate the strange phenomenon that is causing a dimness and a drop in temperature throughout the world. This is the start of a fantastic adventure that eventually takes Burl, a high-school senior, on the first circumnavigation of the solar system. On planet after planet, he and the crew of the Magellan, a gleaming, powerful, and virtually untested spaceship, discover the weird trappings of a brilliantly-designed Sun-tap station. Each planetfall brings unexpected hazards, as the ship draws closer and closer to solving the mystery of the theft.