A nominee for the Hugo Award. The portal between two worlds is open again. The Neanderthal physicist Ponter Boddet returns to our Earth, but now as a messenger tasked with helping the two worlds establish dialogue and cultural exchange. However, the difference in history, social structure, and spiritual values turns out to be a more serious obstacle to cooperation than it seemed at first. Meanwhile, geneticist Mary Vaugan, with whom Ponter resumes a relationship, finds herself in the world of Neanderthals. Now she has a unique opportunity to study a nearly utopian civilization and compare our cultures. “The most important task of science fiction is to show something else. Help imagine the strange and see the familiar in alien images. No one does it better than Robert Sawyer.” — David Brin “It’s a story of love, and also research into physics and philosophy, and in general a novel of big ideas.” — SFRA Review “Robert Sawyer is arguably the best science fiction writer today.” — Rocky Mountain News “This book is worth reading for the quality of the author’s vision and insight—science fiction with virtually no detours, and depth, if not full execution, of his social criticism.” — Quill and Quire