It's been a year since Marlee, her sisters, and the Miles boys survived an avalanche. Sure, it was a little embarrassing for them when all the neighbors saw them on the news, but they love being outdoors, and what are the odds that another tragedy would strike this adventurous group? Has anyone calculated the statistics of being hit with two natural disasters? It has to be low, so of course the two families planned to backpack again this summer. When the teens first meet Thad, a dehydrated hiker on the trail, they give him water and food and help him recover. He seems harmless until he tells them to hike a few extra miles at sunset. Then Lydie finds a hand-drawn map that Thad dropped, and they discover why he is so eager to get away from the Stanley girls and Miles boys. So eager that he starts chasing them. Now they have to climb up unforgiving ridges, sneak through the night, and - is that thunder and lightning? To make matters worse, Marlee has a nagging worry that her older sister Ellie is preparing to move away from home. What is God's plan? How will they get away from Thad before it's too late?