After a mom takes in her recently orphaned niece and nephew, she finds her family in danger when the little girl spirals out of control.

Terri Martin has the perfect life - an adoring husband, a wonderful daughter, and a dream career. Things couldn't be any better. Tragedy strikes when her estranged sister across the country falls down the steps and dies. Her two children, Holly (10) and Michael (7) are orphaned. There is no other family to take them in.

Terri flies out to attend the funeral, and to get to know her young relatives. The children seem traumatized in their foster home, distant from the other kids. Michael hasn't said a word in several months, possibly due to the abuse at home by the hands of his menacing dad before he went to jail. Terri makes a last minute decision to take them home with her so they can once again have a family, as well as a chance to heal.

Problems begin soon after their arrival. Kaitlyn resents her cousins being forced on her. Holly won't stay out of her things. While practicing soccer, Holly purposely fractures Kaitlyn's leg in hopes she can take her spot on her soccer team. While Kaitlyn believes it was done on purpose, her parents brush it off as an accident. Terri gets her neighbor, Mrs. Turner, to watch the kids while Brad and she take Kaitlyn to the hospital.

Mrs. Turner hates kids but is forced into looking after them. During a game of Hide `n Seek, Holly locks the elderly lady in her closet, where she stays until Terri returns. Following a very good innocent act, Terri believes Holly that she had nothing to do with the incident. Later that night, Mrs. Turner falls down her steps and ends up in a coma. While left alone in her hospital room with Holly, Mrs. Turner goes into cardiac arrest.

More issues arise that are possibly related to Holly. Someone changes math answers on Kaitlyn's homework paper and earns her an F. The cat disappears after scratching Holly's face. A bully picking on Michael at school is attacked by hornets. These incidents start to pile up and become very suspicious as Holly has connections to each.

Following outbursts from Holly and her throwing her dinner across her bedroom floor during a punishment, Brad starts to believe that his wife's niece is more disturbed than they could have realized. Getting Terri to believe it won't be easy. A terrible accident kills Brad before he has the chance to speak with Terri again.

After Terri decides to get Holly help, Michael warns her that Kaitlyn is in danger. Terri races to the woods, where she finds Holly about to kill her cousin in hopes she will be permitted to stay with her aunt. Terri is forced to fight for her daughter's life while trying to save her disturbed niece, a feat that may be impossible.