Celeste knows she should be excited to spend two weeks at her grandparents' lake house with her brother, Owen, and their cousins Capri and Daisy, but she's not. Bugs, bad cell reception, and the dark waters of the lake… no thanks. On top of that, she just failed her swim test and hates being in the water-it's terrifying. But her grandparents are strong believers in their family knowing how to swim, especially having grown up during a time of segregation at public pools. And soon strange things start happening — the sound of footsteps overhead late at night. A flickering light in the attic window. And Celete's cousins start accusing her of pranking them when she's been no where near them! Things at the old house only get spookier until one evening when Celeste looks in the steamy mirror after a shower and sees her face, but twisted, different... Who is the girl in the mirror? And what does she want?