Four science fiction stories about keys are selected for this collection from different sources. These tales are designed to be fascinating reading for everyone. The stories are: (1) Old Crompton’s Secret by Harl Vincent (Tom's extraordinary machine glowed - and the years were banished from Old Crompton's body. But there still remained, deep-seated in his century-old mind, the memory of his crime), and (2) The Secret of Kralitz by Henry Kuttner (A story of the shocking revelation that came to the twenty-first Baron Kralitz), (3) The Secret of the Ninth Planet by Donald A. Wollheim (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), and (4) The Very Secret Agent by Mari Wolf (Poor Riuku!... Not being a member of the human race, how was he supposed to understand what goes on in a woman's mind when the male of the same species didn't even know?). This collection consists of three short stories and one rather long story. It is a pleasure to publish this new, high quality, and affordable edition of these timeless stories.