This was a Jason Snell recommendation on a recent episode of The Incomparable that I nearly skipped; I’m glad I didn’t, though, because this was a fascinating book. The premise—that humanity suddenly learns about and how to access parallel worlds to either “side” of Earth—is a fascinating one. In fact, this is the kind of great science fiction that starts with a wild concept and plays with it as long as it can. The plot (and even characters) aren’t as important, and sometimes the book suffers for it, but the concept is so compelling that I couldn’t help but love this. The authors don’t always get Americans, and the audiobook narrator certainly doesn’t, but again: the concept is key, and they do a great job with it.