Ava is having a really bad day. Her parents are getting divorced. She just had a big argument with her two best friends. And she forgot to charge her phone…again.
To top it all off, while she is hiding out in the bathroom over lunch, the alarm goes off for a lockdown drill. Ava knows the rules. She has to get herself into a classroom, turn the ringer off on her phone, lock the door, and cover the windows. But all of the rooms have already been locked from the inside and there is no one in the halls.
Pretty soon, she realizes there is an intruder in the building. This isn’t a drill.