Looking for a narrative book (sci-fi, fantasy, or fiction) for my girlfriend who’s afraid of committing to a long series

My girlfriend loves reading, it's one of her favorite hobbies. However, for the five years I've known her, she's almost exclusively read non-fiction: science, economics, biology, that kind of thing. I know that as a teenager she read more fantasy and sci-fi, Maze Runner, Hunger Games, Harry Potter, the usual, but she drifted away from [...]