Sixteen year-old Shur is one of the first to see the creatures. While staring out the window in history class, she spots one floating over the soccer field. It looks like a monarch butterfly-but it's huge. Within minutes, her classmates' phones are buzzing with emergency alerts. These things are everywhere, and though nobody's exactly sure why the alerts are telling them to take cover, Shur knows it can't be good. It's only when she's left school and headed home that she what the creatures do: they attack.