Lisa Rinna has a terrifying secret in the upcoming Lifetime movie Mommy Meanest.

The film — which was inspired by real-life events — chronicles a teenage girl who is cyberbullied, “only to discover the culprit behind the horrific texts is her very own mother,” according to an official synopsis.

“Divorced mother Madelyn (Rinna) and her daughter Mia (Briana Skye) have always had a tight bond. But when Mia starts spending more time with her new boyfriend and is on the verge of leaving for college, Madelyn is panicked by her emerging independence,” the official description reads. 

“When Mia starts to receive a barrage of degrading texts, as a protective mother, Madelyn is determined to find out who is harassing her daughter and will do anything to help her, bringing them closer together again,” the synopsis continues. “As the hundreds of texts become more threatening, Mia begins to wonder if her tormentor is someone closer than she could have ever imagined.”

The Real Housewives of Beverly Hills alum’s daughter Delilah Hamlin, whom she shares with husband Harry Hamlin, plays Mia’s friend Summer.

The trailer begins with Mia standing in front of her classmates and mother, saying, “We’re all in this together. And bullying has no place in anyone’s lives.” After watching the speech, Madelyn tells her daughter, “You never cease to amaze me” and Mia replies, “I got it from my mother.”

Mia soon starts receiving a barrage of hateful messages and she confides in her friend Summer, saying, “You have no idea the level of message I’m getting” and Summer replies, “I’m really sorry, Mia, for everything that you’re going through.”

A close-up of a text message — which reads “By the time you realize who this is, it’ll be too late” — is seen before it is revealed that Madelyn is behind the messages. 

Despite her secret, Madelyn pretends to be the concerned mother, telling her daughter, “We have to report this and figure out who this is” and “You cannot let one crazy person define who you are.”

Mia realizes the situation is “getting out of control” and asks her mother, “Why do people hate me so much?”

But, Madelyn insists they are “going to get through this.”

Since announcing her exit from RHOBH after season 12 in January 2023, Rinna has returned to acting, appearing in the anthology series American Horror Stories. She executive produced Mommy Meanest in addition to starring in the TV movie. She has also dabbled in modeling, walking in runway shows and appearing in fashion campaigns.

Back in February, Rinna was thrilled to announce she was sharing the screen with her daughter, who made several appearances on the Bravo reality show. “I’m so excited to share this! 😍 🎭🎬” Rinna wrote beside a celebratory post. “Let’s goooooo.”

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

Mommy Meanest airs Saturday, May 11 at 8 p.m. ET on Lifetime.