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Jason Lewis and Rachael Carpani as Christopher and Cathy Sheffield in "If There Be Thorns." The new "Flowers in the Attic" sequel premieres on Lifetime on Sunday, April 5 at 8 p.m. EDT. Lifetime

Brace yourselves, “Flowers in the Attic” fans. On Sunday everyone’s favorite brother/sister couple – Cathy and Christopher Dollanganger – return to Lifetime for the third installment of the V.C. Andrews series, “If There Be Thorns.”

This time around, Cathy and Christopher have changed their last names to Sheffield and are living together in sin as husband and wife. Older than we last saw them, the damaged couple is raising Cathy’s two sons from her previous relationships – Bart and Jory. But while the pair has moved on since their days as children locked in the attic, ghosts from their past threaten to unravel the new life they’ve built for themselves.

Like the second film, “Petals on the Wind,” the third installment in the series was recast as the characters aged. Australian actress Rachael Carpani has taken over the role of Cathy from Rose McIver, while “Sex and the City” heartthrob Jason Lewis has replaced Wyatt Nash as Christopher. Hands down one of the most twisted movies to premiere on TV this year, Lewis revealed to the International Business Times that he actually has a lot of sympathy for Christopher, or as he jokingly called him, “my sister lover.”

“He carried so much guilt for not having been able to do more,” Lewis explained, referring to the “Flowers in the Attic” plot that found the four Dollanganger children locked in an attic by their mother, Corrine. Although two of the Dollanganger’s died, Lewis dished that his character was still “torn” about loving his mother, played by Heather Graham. It was Christopher’s emotions and feelings that really allowed Lewis to connect with his character.

“I found it really easy to understand Chris,” he continued. “I thought here’s a guy who’s trying to do good all the time. He wants to build a foundation for the family he [currently has]. But the same line of adherence of wanting to do good, often times, is what drives him into his problems.”

Although Lewis knew of the V.C. Andrews books, he had not read them prior to being approached for the film. However, he was immediately drawn to the “If There Be Thorns” script, which was penned by Andy Cochran.

“I was kind of unaware of what it was,” he explained of the plot. “I liked the stories from the point that these are characters dealing with very socially ostracizing things.”

With some insanely dark moments throughout the movie, most revolving around 12-year-old Bart (Mason Cook), Lewis revealed that the cast turned to playing music and cracking jokes between filming scenes in order to lighten the mood.

“There are some very painful, twisted paths,” Lewis added of what Lifetime viewers can expect.

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