It's been about a year since the death of her older brother, and now 17-year-old Mari Collingwood (SARA PAXTON) is traveling to her family's remote lake house with her mom, Emma (MONICA POTTER), and her dad, John (TONY GOLDWYN), an emergency room doctor.
Being a swimmer, Mari is excited about having the lake for such use, but she really wants to go see her friend, Paige (MARTHA MACISAAC), who works at the local convenience store. It's there that the two teens meet teenager Justin (SPENCER TREAT CLARK) who offers Paige some pot in exchange for not carding him while buying cigarettes.
Although she initially doesn't want to participate, Mari ends up joining Paige and Justin smoking pot in his motel room. They're having a good time until Justin's dad, Krug (GARRET DILLAHUNT), his brother, Francis (AARON PAUL), and Krug's girlfriend, Sadie (RIKI LINDHOME), arrive, surprised to find the teens there.
And that's because it's their hideout following Krug killing two law enforcement officers who were transporting him to prison before the others freed him. Krug isn't happy with his son's actions, and knowing they can't let the teens go, he and his clan take the girls off into the woods via Mari's SUV. But things go wrong, there's a bad crash, and following that, Krug, Francis and Sadie brutally attack the girls, knifing one and raping and shooting the other.
They then stumble upon John and Emma's house during a bad storm at night, with both parties initially unaware of the others' unlikely connection to the girls.