When the Tuckers' next-door neighbor mentions someone rang their doorbell late the previous night, Sarah and Kenny Tucker check their home's security camera and discover something shocking: the doorbell ringer also visited their house and it wasn't a teenager playing a prank, but instead a terrified young woman with a shackle hanging from her right wrist. She anxiously pressed the doorbell again and again, glancing over her shoulder as if someone was coming for her, before giving up and taking off into the dark.

Almost overnight, she becomes known as The Girl on the Porch—and she's everywhere. There are updates on all the local networks, national coverage on CNN and Fox News, and the video goes viral on social media. Before long, everyone has seen the harrowing security camera footage.

Kenny and Sarah figure it's only a matter of time before someone recognizes the woman, but as the days pass and no one comes forward, odd things begin to transpire around the Tucker family: a man intensely watches them at a restaurant and then vanishes, fresh footprints appear in the garden next to their house where no one should have been, a neighbor's pet is viciously killed and mutilated, and a mysterious man has started following their daughter Natalie . . .