I'll admit, I didn't read the first one. However, this story truly was able to stand on its own - if you didn't know it was the second in a series, you probably wouldn't guess! Brona weaves a clever story over (what seems like) a lifetime, tying the lives of 6 people together in ways that seem entirely too human, too real. It reminded me of the Time Traveler's Wife on steroids, with more science (honestly, the research/imagination that went into this story, wow!). While the story was perhaps a bit slow-moving in the middle third, the last third of the book had my heart racing, and I couldn't put it down. I was worried about getting confused with the different characters (present-character, future-character, etc) and keeping the timeline straight (pun intended), but the author did a great job of clearly communicating to her audience what was happening. Do not fear being left behind! Plus, I'll definitely have to double back to read the first one now.