FX‘s Say Nothing is a searing portrait of the pain and trauma caused by the violent civil war known as “the Troubles” in Northern Ireland. Over the course of nine episodes, the series explores ghoulish murder mysteries, heartbreaking betrayals, and the circumstances that can transform idealistic nonviolent protestors into literal terrorists.

Say Nothing is also a series that plays with tone and focus, pulling us into the romantic rush that young IRA members like Dolours Price (Lola Petticrew), her sister Marian (Hazel Doupe), and Brendan Hughes (Anthony Boyle) felt when they initially joined the frontline fight for the Cause, only to show us the physical, mental, and emotional torture they would later endure because of their actions.

Say Nothing Episode 6 “Do No Harm” is a particularly stunning installment of the series because it focuses specifically on Dolours and Marian as they start serving their prison sentence in England. The sisters immediately demand to be moved to a ladies prison in Northern Ireland, but their request is refused. To protest this, they decide to go on hunger strike, prompting the authorities to force feed them to keep them alive. These sessions are depicted by episode director Alice Seabright as tantamount to sexual abuse and torture.

“It was really scary to take on that episode,” Say Nothing star Lola Petticrew told Decider. “It felt like a lot of responsibility for people back home, for what these two women went through, for the trauma that their bodies went through, and mentally what they went through was basically torture.”

Over the course of Say Nothing Episode 6, Lola Petticrew and Hazel Doupe had to capture the pain of starvation, the horror of force feeding, and, ultimately, nearly dying of malnutrition. Say Nothing never fetishizes the Price sisters’ weight loss, but manages to convey just how ill and emaciated the young women got during their hunger strike. Petticrew praised the production team behind the series as well as the crew, whom they called their “saving grace.”

“We had a lot of protections in place. We had intimacy coordinators and stunts. We had a good bit of rehearsal time. Our director on that episode, Alice Seabright, was just a star,” they said. “And a lot of it was done through prosthetics and makeup.”

“The whole way through that process, we just, as a unit, everybody involved in making show, were in conversation about the best way to do this honestly and also respectfully and also safely. So I felt very taken care of. My priority was making sure that I was taking care of the storytelling of what happened to Dolours and Marian. And then very much everybody else felt like they were taking care of me.”

Throughout Say Nothing Episode 6 — and, in fact, the whole series — the Price sisters survive by relying upon each other. While older sister Dolours always seems to be leading the duo, “Do No Harm” shows that Marian might be the stronger sister. She not only wants to continue with the strike when Dolours wavers, but Marian almost dies. Marian’s extreme commitment to the Cause becomes a running theme, if not defining feature, of Say Nothing.

“That was something that Hazel and I discussed a lot from the beginning,” Petticrew said. “Dolours was the older sibling and felt very much like she was in charge, but at a certain point in the series, you see that shift and you see Marian take a lead on things a lot more.”

Petticrew went on to point out that the biggest difference between Dolours and Marian on the page was simply “Marian’s capability to compartmentalize in a way that Dolours maybe just couldn’t quite get.”

“For Dolours, I think everything that she went through and the trauma — not just what she had done, but of what happened to her and her body — I think that Marian was able to compartmentalize in a way that Dolours maybe wasn’t.”

For viewers to understand all that trauma, Say Nothing had to put Petticrew and Doupe through the wringer in “Do No Harm.”

“I think it was really an incredible feat to pull off what we did,” Petticrew said. “And I’m really proud of it.”

Say Nothing is now streaming on FX.