An unabridged collection spotlighting the "best of the best" hard science fiction stories published in 2018 by current and emerging masters of the genre, edited by Allan Kaster. In "3-adica," by Greg Egan, sentient characters in an online multiplayer game hack the operating systems of their host machines to escape to a refuge that's only rumored to exist. Struggling colonists, on a world subject to periodic bursts of radiation from its primary's UV-emitting companion, go on an expedition to recover a critical package from Earth in "Umbernight," by Carolyn Ives Gilman. In "Icefall," by Stephanie Gunn, the Mountain on the planet, Icefall, holds the mystery to a lost colony and is an irresistible, fatal allure to the climbers of the universe; but no one ever returns from the Mountain. A mother seeks revenge on the doctor that changed her neuro-atypical son's personality with a deep brain stimulation implant in "The Woman Who Destroyed Us," by S.L. Huang. In "Entropy War," by Yoon Ha Lee, a conquering alien race at the height of their powers, retreats into an arkworld to win the ultimate war in the only way they can. An AI piloting an island-ship, that used to be the Earth, struggles to make sense of the universe as the last stars are dying out in "Cosmic Spring," by Ken Liu. In "Nothing Ever Happens on Oberon," by Paul McAuley, set in the author's Quiet War universe, a supervisor of a mining operation on the moon, Oberon, investigates the crash-landing of an ancient escape pod. In depression-era Alaska, a desperate bush pilot reluctantly accepts an illegal charter from a pair of scientists investigating a legendary mirage in Glacier National Park in "The Spires," by Alec Nevala-Lee. In "Providence," by Alastair Reynolds, the crew of a crippled starship, unable to complete its mission, decides to salvage its expedition by providing future exploratory ships with data they did not have. A disillusioned crèche manager leaves Luna to work on an asteroid-based crèche and then must decide whether or not to return to Luna in "Intervention," by Kelly Robson. And finally, an entity that controls the solar system wants aid against another entity from a reconstructed human it just created, in "Kindred," by Peter Watts.