Alex is a 17 year old girl with a brain tumor. She knows that her life is at its end, so she decides to hike into the wilderness to spread her parents' ashes, while she is still healthy enough to do so. However, everything changes in an instant when an electromagnetic pulse flashes, destroying every electronic device, wiping out every computerized system, and killing billions. Alex joins forces with Tom, a young soldier on leave, and Ellie, an 8 year old girl who lost her grandfather to the pulse. Alex, Tom, and Ellie soon discover that the pulse changed some of the survivors for the better, while others were turned into ravenous zombies. Not only do they have to protect themselves from the changed, but they also have to protect themselves from survivors who will ruthlessly do whatever it takes to survive, even if it means killing and stealing from other survivors.
