What does the perfect family have to fear most? The perfect stranger.

From the outside, Frank and Grace seem to have the perfect family. He's a loving husband, she's a devoted wife, and together they have two happy children. But appearances can be deceiving. A strange series of misfortunes has left them reeling: an unexplained break-in, a catastrophic accident, and a bizarre poisoning that's left Grace feeling especially unnerved. Packing up their RV for a move across the country, they're ready for a fresh start, expecting to leave all their problems safely behind.

Then one night on the road to their new home, the figure of a young woman emerges from the darkness, causing them to swerve off the road. The injured stranger says her name is Mara. Miles from help, they invite her to stay. But Mara is hiding a secret. And she is not the only one.

Was it all just another inexplicable accident? Or have they opened the door to an escalating family nightmare designed to tear their perfect world apart?