"It's a really painful decision to make, but it's ultimately one of the most selfless things that she's done," Maslany tells THR of Sarah's heartbreaking choice.

[Warning: This story contains spoilers from Orphan Black's "Transitory Sacrifices of Crisis" episode.]

Sarah's (Tatiana Maslany) tug-of-war between her immediate family unit versus trying to protect her "sisters" took a dramatic turn during Saturday's Orphan Black.

During last week's season three premiere, Sarah made the decision to push away Mrs. S (Maria Doyle Kennedy) for turning in Cosima, even though it was done in an attempt to keep Kira (Skyler Wexler) safe. Unfortunately, Mrs. S' decision didn't yield results for as long as they hoped, and in this week's episode, Kira's life was put in jeopardy when male clone Rudy (Ari Millen) broke into their home.

With the prospect of not being able to properly protect her daughter looming, Sarah opted to send Kira off with her father, Cal (Michiel Huisman), in the hopes of keeping them both safe.

"It takes a lot for her to make that decision," Maslany told The Hollywood Reporter. "Ultimately, the biggest gift she can give Kira is to make sure she's safe. That can't happen when Sarah's around her, because it makes her a [target] — she threatens her life just by being near her. It's a really painful decision to make, but it's ultimately one of the most selfless things that she's done."

While Sarah is mourning her daughter's absence, what she doesn't know is that her sort-of ex, Paul (Dylan Bruce), reached out Cal to warn him to keep the family unit safe.

"[Paul's] arc this season is really surprising," Maslany said. "[Bruce] does some really beautiful amazing work, and it was great to see his character expanded and explored. We get a little more into why he's doing what he's doing, and what he's even doing in the first place. We get to know Paul a little bit better. And I think fans are going to enjoy that."

Orphan Black airs Saturdays at 9 p.m. on BBC America. What did you think of Sarah's decision to send Kira away?