Don't just fear what you're hiding from, fear what you're hiding with.
Cassie's night of babysitting goes to hell, when bombs explode in the distance, planes fly overhead at low altitudes, and alerts on her phone tell her to seek shelter. Luckily, the boy she babysits tells her his father has a bunker in the yard.
When they make their way to this underground shelter, they soon discover they aren't alone. Something is living in the bunker, and it isn't happy to share the space with Cassie.
