Horizon is a fitting conclusion for Sophie Littlefield's Aftertime series. I was thrilled to see the zombies make a significant return for the finale.The only flaw I found with Horizon and the Aftertime series as a whole was a lack of connection to the characters. Cass Dollar was pretty different in each book, and I never managed to like any of the versions of her.Thankfully I loved the story, and I found unforgettable moments throughout the series. I do recommend you read Aftertime and Rebirth before reading Horizon. There is a novella, Survivors, between the first two that I recommend as well, but it's not necessary.Littlefield has created such an epic world within the Aftertime series. Even though we are left with a resolved ending and so many answers were given in Horizon, it feels like the series could go on forever. I can close my eyes and picture what's happening in the Aftertime world right now. It makes me sad that the series has ended which is always the mark of a great read.