Walter and Paige just became an official couple in “Scorpion” Season 3, but it seems that a newcomer will try to break them apart in Season 4.

According to TV Line, CBS just cast “Grey’s Anatomy” alum Tina Majorino in a major guest-starring role as Florence. Details about Florence are still being kept under wraps, but she is revealed to be a chemist who will move in next to Walter( Elyes Gabel) and his team.

At first, Florence will find it difficult to immerse herself into what Walter and the Scorpions are doing. But once she gets accepted by the gang, she will cause some tensions between all of them, particularly Paige (Katharine McPhee) and Walter.

Majorina starred in “Veronica Mars” as Cindy Mackenzie and “Grey’s Anatomy” as Heather Brooks. She also appeared in “Big Love,” “Bones” and “Legends.”

Meanwhile, the cast of “Scorpion” Season 4 are still on the set filming for their upcoming episodes. The production for the hit CBS TV series kicked off in July. Last month, “Scorpion” cast member Ari Stidham shared some details from the premiere episode and said that it will center on Sylvester and Megan (Camille Gauty).

“There’s a good amount of Megan O’Brien in the first two episodes. The character doesn’t come back, but there’s a lot of stuff for Sly as far as Megan goes,” he told TV Line.

Megan passed away in the previous episode of “Scorpion” after she tied the knot with Sylvester. Megan also happens to be Walter’s sister so he and Sylvester share a special bond with each other. The titles for “Scorpion” Season 4, episodes 1 and 2 have also been released via Spoiler TV. Episode 1 is called “Extinction” and episode 2 is titled “More Extinction.”

“Scorpion” Season 4 will also shed light on the future of Toby (Eddie Kaye Thoms) and Happy’s (Jadyn Wong) marriage. According to showrunner Nick Santora, it’s possible for the two to think about having children. He said that Happy’s pregnancy is a natural progression for the married couple, but it’s not something they want to rush into.

“Scorpion” Season 4 will premiere on CBS on Sept. 25 at 10 p.m. EDT.