Charles Yu, time travel technician, helps save people from themselves in Minor Universe 31, a vast story-space on the outskirts of fiction. When he's not taking client calls, Yu visits his mother and searches for his father, who invented time travel and then vanished. Accompanied by TAMMY, an operating system with low self-esteem, and a nonexistent but ontologically valid dog named Ed, and using a book titled "How to Live Safely in a Science Fictional Universe" as his guide, Yu sets out, and back, and beyond, in order to find the one day where he and his father can meet in memory.