Inconceivable is a 2017 American thriller film directed by Jonathan Baker and written by Chloe King. It stars Gina Gershon, Faye Dunaway, Nicolas Cage, Nicky Whelan and Natalie Eva Marie. The film was released on June 30, 2017, by Lionsgate Premiere.

While holding a crying baby, a woman fights with and kills a man. Four years later, Angela (Gina Gershon) and Brian (Nicolas Cage), both doctors, have a four-year-old daughter named Cora. Angela's friend Linda (Natalie Eva Marie) introduces Angela to Katie (Nicky Whelan), who has a four-year-old daughter, Maddie. Katie says she left an abusive husband but does not elaborate. Brian's mother, Donna, (Faye Dunaway) dislikes Katie from the start and questions her background.

Devastated after a miscarriage, Angela invites Katie to move into the guest house and be a part-time nanny while she recovers. One night, knowing Brian is watching, Katie steps naked into the pool. Brian becomes uncomfortable and leaves. When Angela returns to work at the hospital, Katie watches Cora.

Katie snoops through Angela and Brian's belongings. Angela comes home after work one day and catches Katie having sex in the guest house with whom she thinks is Brian, but is actually a woman. After the initial embarrassment, Angela relaxes somewhat and trusts Katie more, not believing she would ever have any interest in Brian. Linda excitedly tells Katie that Angela is going to ask her to be their surrogate, but Katie can barely hide how much it upsets her.

Angela has one embryo left from the same donor that Cora was conceived from, and she wants to use that so the two can be full siblings. Katie confides to Linda that she is the donor, and that her daughter Maddie was also hers but born from a mother in Maine. Katie abducted Maddie as a baby because "the mother didn't take care of her" and now she worries that Cora is not getting enough attention either and wants to take her. She clubs Linda over the head and drowns her in a lake. A couple later finds her body.

Months later, Angela and Brian tell Katie they are getting a full-time nanny, and Katie accuses them of wanting a complete stranger to raise their child. Angela suspects Katie is planning to keep the baby and disappear, and accuses her of killing Linda because she wanted it for herself. Katie fakes early labor pains. Brian is furious with Angela and is told by Katie that she is taking illegal prescription meds and losing her mind.

The next morning, while Brian is at work, Angela sneaks into the guest house and discovers Katie's secrets, confirming that she was a previous donor; she then gets a DNA test for the girls. While dropping off the DNA samples, Angela becomes very light headed and woozy, and tries to rush home, but then passes out while driving. Once she wakes, she realizes that Katie has drugged her and rushes home, where she confronts Katie, who admits everything to Angela and stabs herself in the stomach, then screams for Brian while stabbing Angela. Katie says she is going to tell everyone that Angela tried to kill her and Angela tells Katie that the truth will come out.

Katie is taken to the ER and an emergency C-section takes place. A healthy baby boy named Gabriel is born. The DNA test comes back and shows that Maddie and Cora were related to each other and to Katie, meaning Angela had told the truth. Katie is arrested then shown in a padded cell whilst the happy family of Brian, Angela, Maddie, Cora and Gabriel are shown all resting together.