A human detective and their partner, an enhanced chimpanzee, investigate a strange murder on the subway ... a smart home goes into lockdown, turning a man's own home into his prison ... at a robot factory, something has caused the machines to attempt to escape ... lien invasion ... a woman seeks to restore a broken AI, hoping it can help return humanity to better days ... For decades, science fiction has compelled us to imagine futures both inspiring and cautionary. Whether it's a warning message from a survey ship, a harrowing journey to a new world, or the adventures of well-meaning AI, science fiction inspires the imagination and delivers a lens through which we can view ourselves and the world around us. With The Best Science Fiction of the Year: Volume Four, award-winning editor Neil Clarke provides a year-in-review and twenty-nine of the best stories published by both new and established authors in 2018.