I do agree with other reviews that this book starts strong and loses itself slightly. but the ending feeling slightly rushed doesn't ruin the book for me. It's such a interesting read, the way time travel is built into the world makes the book. The author clearly had strong ideas about how time travel would change society and it keeps the sci-fi feel without being too out there. The story remains grounded for the most part (i don't love the genies, especially the books) and really focuses on how time travel might affect individuals. One thing is: the murder mystery feels misplaced? It almost doesn't need to be there because the world around the concave is interesting enough without the murder plot. Id have honestly read a book with more stories like Fays or Gingers that show the consequences being able to travel through time would have for mental health and interpersonal relationships.