The Stepdaughter Plot Summary
The film centers on Joanna, a teenager who is grieving the loss of her mother and grandmother, her two closest family members. Joanna’s birth father, Michael Lawrence, is a successful man who has recently married Whitney, an equally successful businesswoman. Feeling alone and with no one to turn to, Joanna decides to show up at her father’s house.
Whitney, being kind-hearted, offers Joanna a place to stay for as long as she needs, which Joanna accepts. Lawrence introduces Joanna to her stepbrothers, who are excited to meet her. However, Joanna’s expression reveals that she is not there to join the Lawrence family but has other evil intentions.
How does Joanna try to ruin Whitney & her family?
The day after Joanna moves in, Whitney’s mother’s urn, containing her ashes, breaks into pieces. Initially, Joanna is reluctant to accept her mistake but eventually confesses to breaking the urn. Whitney understands Joanna’s initial hesitance and doesn’t hold it against her. When Whitney shares these events with her sister Cass, she suggests doing a background check on Joanna for safety reasons.
However, Whitney dismisses the idea. The next day, Joanna notices Whitney preparing samples of her cosmetics products to pitch to Walmart for a worldwide display. The presentation takes a disastrous turn when one of the models experiences a severe allergic reaction, resulting in facial burns. Whitney tries her best to salvage the deal, but the damage is done. The deal falls through, and Whitney’s cosmetics line suffers a significant setback.
At night, someone swaps Joanna’s fluvoxamine tablets, which she takes for her OCD, with something else. Whitney unknowingly consumes the substituted tablets and begins to feel dizzy and tired. Lawrence offers to cancel his real estate conference to take care of her, but Whitney insists that Joanna and the kids can take care of her.
Eric becomes suspicious of Joanna when he catches her trying to steal Whitney’s credit card. Joanna threatens Eric, warning him to forget what he saw if he wants his mother to remain unharmed. Later, when Whitney asks about her missing credit card, Joanna manipulates the situation to make it seem like Whitney is accusing her of theft.
That same night, Joanna gives Eric, who is only eleven, a beer laced with something that knocks him unconscious. She then attempts to throw him into the pool but stops when she sees Lawrence. However, this incident is just the beginning of Joanna’s sinister actions. Disguised, she purchases items like ropes, duct tape, and plastic sheets that criminals use for kidnapping and disposing of the body.
Furthermore, when Dante, a friend of Brian’s, finds Joanna’s diary, she kills him by striking him on the head with a blunt object.
Why do Whitney and Michael have a fallout?
Whitney receives a call from the lab where she has sent her cosmetics samples to be tested. She learns that while most of the batch is fine, some products have a high concentration of sodium hydroxide, a highly toxic substance. Whitney knows she would never use such chemicals in her products and begins to suspect Joanna.
Whitney asks Cass to do a background check on Joanna. It is later revealed that Joanna’s real name is Maggie Dillon. When Whitney asks Lawrence about the same, he explains that Joanna’s grandparents changed her name when she moved in with them.
Whitney tries to explain to Michael that Joanna has been sabotaging her life, but they have a fallout over the issue. Whitney is now certain that Joanna/Maggie is behind the sabotage of her cosmetics line.
Why does Whitney end up in hospital?
Joanna is determined to destroy Whitney’s family. She drugs Whitney and slashes her wrist, framing her as an unstable and suicidal person. However, Whitney survives the attack and asks her sister Cass to take her sons, Brian and Eric, home with her. While in the hospital, Whitney learns that Joanna has been mixing her prescription drugs with cocaine.
This information is reported to social services, putting Whitney at risk of losing custody of her children. Additionally, Whitney is informed about Dante’s death, and Cass confirms that Joanna is responsible. Cass drives to Whitney’s house to gather evidence against Joanna, but Joanna pushes her off the first floor.
What happens in the end?
Joanna calls Whitney and gives her an ultimatum. She orders Whitney to meet her at the house, or she will harm Eric and Brian. When Whitney arrives, Joanna incapacitates her and reveals her sinister plan. She confesses to pushing her Granny down the stairs, making it look like an accident, and now plans to kill Whitney and her family and frame her for the murders.
However, Joanna is not acting alone. She reveals that her partner in crime is her father, Michael Lawrence, who has a history of marrying wealthy women, killing them, and inheriting their money. Whitney is just one of Michael’s many targets. However, when Joanna learns that Michael is responsible for the death of her mother as well, she loses her cool.
All this time, Joanna had believed her mother was killed by a drunk driver, unaware that Michael had orchestrated her death. To get her revenge, Joanna drugs Michael, but he regains consciousness and attacks her. Thankfully, Whitney wakes up and shoots Michael in the back, saving Joanna and herself. As the film nears its end, the cops arrive, and Joanna is rushed to the hospital, but Michael manages to escape before he is put in handcuffs.