The bizarre and twisted story of Cathy and Christopher Dollanganger continues tonight on Lifetime. The third movie in the “Flowers in the Attic” series, “If There Be Thorns,” premieres at 8 p.m. EDT – and viewers definitely won’t want to miss it.

Lifetime kicked off their adaptation of V.C. Andrews’ book franchise in January 2014 with “Flowers in the Attic.” The flick introduced the Dollanganger children – Cathy, Christopher, Carrie and Cory – who had two loving parents and a beautiful home before a tragic accident turned their lives upside down. With money issues threatening to put the Dollanganger kids out on the street, their mother, Corrine, turned to her estranged parents for help. But in order to receive her hefty inheritance, Corrine had to keep the existence of her children a secret … so she locked them in the attic.

After three years in the attic, the children finally managed to escape. However their lives would never be the same. Cory died, Carrie was depressed, and Cathy and Christopher developed a forbidden relationship.

The second movie, “Petals on the Wind,” premiered last May and kicked off 10 years after the events in the attic. Although Cathy, Carrie and Christopher had moved on with their lives, their time locked up continued to haunt them.

Cathy followed her dreams to become a famous dancer and moved from South Carolina to New York with her boyfriend Julian, a fellow dancer. Their relationship was tumultuous, with Julian extremely jealous, possessive and abusive of his girlfriend. Meanwhile, Christopher tried to move on from his feelings for Cathy with a local woman named Sarah. But despite Sarah’s sweet demeanor, nothing could stop Chris from thinking of his sister.

As Cathy and Christopher found “love,” Corrine was enjoying married life with her new husband, Bart. However the couple had their problems – like Corrine’s ill mother. While Bart had sympathy for the old woman, Corrine couldn’t care less if she didn’t eat or bathe. Corrine and Bart’s relationship became even more strained when she revealed that she had started a large renovation on their home, Foxworth Hall.

Cathy ultimately became pregnant with Julian’s child, but Julian didn’t live to see the baby born. He was killed in a car accident after getting into a fight with Christopher. Cathy moved back to South Carolina shortly after to be with her brother and sister and raise her son, Jory. Unfortunately bad luck continued to follow the Dollanganger kids.

Although Carrie found herself a sweet man to marry, she couldn’t get over the rejection of her mother. The final straw was when she approached Corrine about coming to her wedding. Corrine turned her back on Carrie, telling her that she must be mistaken because she has no daughter. Carrie killed herself the next day the same way that her twin brother Cory died – by eating a poisoned donut.

Cathy vowed to get revenge on Corrine and hatched a plan to seduce her mother’s new husband. That plan didn’t sit well with Christopher, and the pair stopped talking while Cathy grew closer to Bart. She succeeded in having an affair with Corrine’s husband, and even got pregnant.

The brother and sister finally reunited before Christopher’s wedding to Sarah. Even though they both were in relationships, nothing could stop the feelings they had for each other. Although Cathy told him that Sarah was perfect, Christopher countered that Sarah couldn’t compare to her. The pair engaged in a heated kiss … that Sarah walked in on.

Needless to say, Sarah called off the wedding to Christopher and word spread around town that the siblings were involved in a romantic relationship. Christopher asked Cathy to move to California with him to start a life together. But Cathy told him no – and broke the news that she was pregnant with Bart’s baby.

She insisted to her brother that she was in love with him and not Bart. However she had to “finish what she started.” Cathy attended the annual Christmas party at Foxworth Hall and exposed Corrine’s dark secret. In a crowded room, Cathy revealed to Bart exactly what Corrine did all those years ago. Corrine initially denied Cathy’s claims, but then tried to give excuses when her own mother failed to back her up. If that wasn’t bad enough, Cathy told everyone that her mother’s husband got her pregnant.

Bart was horrified at the news and told Corrine he needed time to think. While he sat down with Cathy, Corrine confronted her mother about the events in the attic. She claimed that it was her mother’s fault that she lost her children, and had a mental breakdown when she found Cory’s body in a trunk. She set fire to her mother’s room and fled Foxworth Hall with Chris. Bart ran upstairs to rescue Corrine’s mother, but never made it out of the building alive.

“Petals on the Wind” ended with a six-year time jump. Cathy and Christopher moved to California with Cathy’s two children, Jory and Bart. They were living as husband and wife while a mentally unstable Corrine remained locked up in an institution.

“If There Be Thorns” will reintroduce an older Cathy and Christopher as they raise Bart and Jory and try to keep their dark past hidden. However everything starts to fall apart as Bart befriends their mysterious new neighbor – Corrine.

“If There Be Thorns” will air on Lifetime on Sunday, April 5 at 8 p.m. EDT.