This collection includes two short science fiction novels written by Catherine Moore. The stories are: (1) Song in a Minor Key (He had been promising himself this moment for how many lonely months and years on alien worlds?), and (2) The Tree of Life (A gripping tale of the planet Mars and the terrible monstrosity that called its victims to it from afar—a tale of Northwest Smith). It is a pleasure to publish this new, high quality, and affordable edition of these timeless stories.