When a college freshman connects with the mother of her birth mom, she believes things couldn’t be better until her new grandma grows controlling and threatens to destroy everything she loves.

18-year-old Carly gives birth in a hospital to a baby girl. Not wanting to be a mom, she has already arranged for her daughter to be adopted by a well-off couple. The problem is that she hasn’t told her parents. Excited to be grandparents, Betty and George are devastated when they arrive at the hospital and learn there is no baby to hold. Betty vows to cancel the adoption but can’t since her daughter is an adult.

Carly’s social worker, Sandra, walks her dog. Someone hidden beneath dark clothing kills her and throws her body into a pond.

18 years later, the baby has grown into Zoey Griffin. Raised by a successful couple, she has just started college on a partial softball scholarship. Things are great but get even better when Betty finally locates her granddaughter and wants to be a part of her life. After taking a DNA test to prove they are related, Zoey welcomes her grandma into her life. Betty is very generous with her new relative, taking her shopping, on trips, and even buying her a brand new car.

The boy Zoey likes, Brent, grows distant. He no longer answers Zoey’s texts. Seeing this as an opportunity to drive the young man out of Zoey’s life, Betty tells Zoey that proper young men don’t like girls who play dirty sports. Believing her grandma, Zoe tries to have it all by pretending to have a back injury so she can be off the team for a while without losing her partial scholarship. The dean grows suspicious and calls Zoey’s adoptive mom, Sheila.

Sheila confronts Zoey and tells her to straighten it out. After seeing Betty at one of Zoe’s games, loudly cheering for “her granddaughter”, Sheila and her husband Dennis push Zoey for the truth. She admits who Betty really is. While Zoey’s parents are upset over the revelations, Zoey reminds them that she is 18 and can do what she wants.

Betty’s attempts to break up Zoey and Brent become obvious, causing friction between the two people Zoey cares for. Sheila continues to push Zoey into dropping Betty from her life. After an altercation, Betty attacks Sheila on campus and makes it look like a robbery. Sheila is placed in an induced coma with Zoey rushing to her side.  

The same night, Betty attacks Brent but he puts up a fight and fends her off. While he didn’t get a good look at her, he tells Zoey he believes she was his attacker and she hurt her knees. When Zoey sees Betty limping, she knows how dangerous the woman really is, but it’s too late. Betty drugs Zoey and hides her away inside a bunker she recently bought.

Sheila sneaks out of the hospital and uses a location app to track Zoey to the woods. When Betty leaves the bunker, Sheila attacks but loses the battle. Inside, Zoey teams up with her mom to take Betty out. They figure out the door’s code and escape. Zoey then eagerly returns to her old, boring life.