Hannah Steele loves living on Pelling, a tiny island near Seattle. It's a little disconnected from the outside world, but she's always felt completely safe there. Which is why when she's asked one day to babysit after school, she thinks it's no big deal. Zoe and Oscar are her next-door neighbors, and Hannah just took a babysitting class that she's pretty sure makes her an expert. She isn't even worried that she left her inhaler at home. Then the shaking begins. The terrifying earthquake only lasts four minutes but it changes everything, damaging the house, knocking out the power, and making cell service nonexistent. Even worse, the ferry and the bridge connecting the kids to helpand their parentsare both blocked. Which means they're stranded and alone... With Hannah in charge, as things go from bad to dangerous.