The season finale of Starz's "Outlander" is going to make a lot of fans cringe, as Jamie's torture in the hands of Black Jack Randall is far from over.

The finale episode entitled "To Ransom a Man's Soul" will see Jamie escaping Black Jack's clutches, but the torture he endured in the prison will leave him scarred for a while.

"Jamie's very much affected by this," the actor told TVLine. "If you've read the books [by Diana Gabaldon], you know that." Heughan added that he was happy with how the scene turned out, but switching off from the dark place his character's mindset was a difficult thing for him to do.

"I needed to decompress after a couple of weeks. It was pretty tense," Heughan said. In order to relax, the actor climbed seven of Scotland's lower-lying mountains in a day, and it "was really a nice way to clear the mind."

The finale is going to be dark and graphic, and executive producer Ronald D Moore noted that they haven't shied away from showing certain controversial scenes that showcase Jamie's suffering.

"The most important thing, fundamentally, was to tell that part of the story as truthfully as we possibly could," executive-producer Moore said. What actually takes place between Jamie and Black Jack, such as the torture, rape and mind games, will have a profound effect on Jamie's relationship with Claire, and the show has tried its best to stay close to its source material, Moore said.

 "This is tricky material, very harrowing material, but we wanted to play the truth of what really happened between these two… and to find that line where you're neither being gratuitous, and you're not shying away at the same time — where you're showing what needs to be shown, and you're not afraid of it, but you're not reveling in it."

He added: "You have to find that tone, and it just took a lot of time."

"Outlander" season finale will air Saturday on Starz. According to the official synopsis of the episode Jamie is freed, but the torture he endured in the prison lingers.