Seventeen-year-old Icie's parents have given her $10,000 in cash, a map of a top-secret bunker, and instructions to get there by any means necessary. They have news of an imminent viral attack and know that the bunker is Icie's only hope for survival. Along with three other teens, she lives locked away for months, not knowing what's happening in the outside world or who has survived. And are they safe in the bunker after all? Generations in the future, a mysterious cult worships the very mountain where Icie's secret bunker was built. They never leave the mountain, they're ruled by a teenager, and they have surprising ties to Icie.Half Lives is a fast-paced and high-stakes glimpse into what the future could hold, into the strength of humanity. Two rather compelling stories unfold along each other, revealing both the end of the world as we know it as well as what it could become hundreds of years from now.I found this to be a rather original idea. It wasn't just one girl's mission to stay safe, to stay alive, or one boy's task to keep his people safe, to continue their way of life. It was more of a reveal over time, a reveal of both their characters and their worlds. Both timelines are about survival and what it is to be human, what it is to live in a time and place uncertain and potentially dangerous.Icie is on a journey to survive, to follow the path her parents set before her in order for her to survive what they know is coming. She has a purpose forced upon her, and it is to keep on living. Along the way she meets three other teens and her tale then includes discovery and the new 'world' they create. But how long is long enough? How long can you go on knowing the world around you is dangerous, is crumbling, and everything you once knew is gone? And how safe is the bunker Icie's parents sent her to?Beckett doesn't necessarily start on a journey, but it turns into one. A journey to keep his people and their home safe from what lies out away from the mountain in the ruins of a civilization broken and filled with danger. A journey to keep the mountain safe, to follow the teachings of the one they worship and to keep on living. But not everything is as it seems. The mountain holds secrets. And there are lights in the distance. What is out there? What is coming? What is the truth hidden in the mountain?Both timelines intertwine, alternating between Icie's trek into the desert and Beckett's mission to keep everyone safe. Questions are raised an answered over time, in both Icie's and Beckett's time. Words and phrases of Icie's live on in the future, clearly passed down through generations of survivors and human beings born after the event, but how were they influenced by her? And why? Where did she stop and they begin? The future is a curious place.The human spirit is strong, it fights to survive, to adapt, to continue living when things are at their bleakest. Instead of giving up and wasting away we still go on, we still help others, still teach others how to live, how to read, how to survive. Names may be forgotten, worlds may take on different meanings, priorities may change, but the drive to live on will always be there.I was tempted to first read Icie's chapters, to learn her story before going back to read about both her and Beckett at the same time, but I didn't. I think the reasoning behind books like this, books where chapters alternate between points of view and points in time, is that as different as the characters are they have their similarities, that they're tied together in ways they don't realize. They they will face obstacles, face danger, face death, and they must draw from inside themselves to keep on living not just for them but for those that depend on them. For the future.