'His Dark Materials' Cast on 'Bittersweet' Goodbye to HBO Show

His Dark Materials is coming to its epic conclusion with the adaptation of Philip Pullman's The Amber Spyglass, the final book in his trilogy, and it proved to be a "bittersweet" goodbye for the cast, they told Newsweek.

The HBO show returns with its first two episodes on Monday, and it will pick up where Season 2 left off: With Lyra Belacqua (Dafne Keen) missing after being taken by her mother, Mrs. Marisa Coulter (Ruth Wilson), and Will Parry (Amir Wilson) searching for her.

Keen, Wilson, James McAvoy and Ruth Wilson spoke to Newsweek about bringing the story to its conclusion, and what is in store for fans in Season 3.

'His Dark Materials' Cast on 'Bittersweet' Goodbye to HBO Show with Season 3

Lyra's arc as the prophesized new Eve and Will's as the bearer of The Subtle Knife will come to a head in Season 3, and the series will see them go on their most dangerous journey yet, one that will take them to a dark place that no one else has ever been able to return from.

Ruth Wilson told Newsweek how sad she was to be bidding farewell to the franchise after just three seasons, even if it follows the story as plotted out by Pullman in his original children's book series.

Sharing her thoughts on finishing making the series, Wilson said it was "kind of bittersweet," but added: "It's really nice to solve all those things, those puzzles and those storylines and those relationships, but also yeah [it's] sad to see it go and to not work with those people again. Well, not on this iteration anyway."

Of the show ending, Amir Wilson added: "It's kind of satisfying in a sense that people are finally able to see it, but it's also a sad ending, I guess.

"I'm not allowed to say too much, but I'm excited for everyone to see what us, and all the cast and all the crew of worked six months of hard work for."

While it was difficult to say goodbye to the series, the cast's last day on set felt like "any other day," Keen said.

"I have this very weird sense of like pride for what we created like as a team," the Logan star shared. "It's that sense of we're happy that we were able to tell the story and being so happy and how well [it went] and feeling really proud of what we created together."

Amir Wilson added: "Suddenly it was over. It was like, 'that's a wrap' and it wasn't necessarily that it was really emotional at the time, it was just everyone would come out and we would just say goodbye to some people.

"The next day, we had the wrap party, we would go to properly say goodbye to some people and [the crew] showed us some of the stuff that we had shot so far, and it was nice. I guess it doesn't really hit you until moments like these when you're talking to people about it."

What to Expect in 'His Dark Materials' Season 3 From Lord Asriel and Mrs. Coulter

In the new season, Lyra's father Lord Asriel (McAvoy) is amassing his forces to embark on his great war against the Authority and his angels, while Mrs. Coulter is on her own journey of redemption.

For Ruth Wilson it proved to be an interesting challenge to go from villain to antihero, but it was one that she had been preparing for from the very beginning.

"I always knew we had to get there because she ends up doing right by Lyra and by the world, and ends up combining with Asriel to do that," Wilson teased. "But also, she ends up sort of reconciling with herself, with [her daemon] monkey.

"[There's a] moment in the book when he speaks for the first time and they hold each other, I [thought] 'okay, I have to go from her hitting herself, or hitting monkey, to her holding and embracing her monkey,' a great arc of personal growth that she has to do over the course of three seasons."

In Pullman's novels, Lyra's world is special because people's souls are split into two. One half is known as a daemon, an anthropomorphic representation of a person's soul that settles its form during their adolescence. Mrs. Coulter's daemon is a golden monkey.

Wilson went on: "I loved that that was coming to its full [conclusion], everything we've built in the first two seasons had to pay off in three and I think we did do that because in Season 2 she's really dastardly, she's the worst in Season 2, and then [Season] 3 was about 'how do you make her a goodie? How do you make her intentions be good suddenly?'

"Which was actually harder to play than you think because it's sort of less interesting, playing bad is really fun because it's complex and nasty and, you know, you get to wear heels, and suddenly I was wearing flat shoes and I was a goodie in woolly jumpers, and I thought 'oh, this isn't as fun.'"

Despite this, Wilson added: "It was great, it was really satisfying. The whole journey was really satisfying."

All the while, Lord Asriel is so determined to defeat the Authority and save every world under his control that he has little thought for anything else, including his daughter Lyra.

"I don't think he's blinded by his ambition; he's blinded by the profundity and the righteousness of his goal but, nonetheless, he is blinded," McAvoy reflected on his character's journey in Season 3.

"I don't think it's a new thing that that blind outlook is making him not value his daughter, I think he spent her entire life not valuing her, making her not even secondary or tertiary.

"And I think in this [season] he has been able to sort of forget about her, [he] even gets over the rejection that he suffered from Mrs. Coulter because he is the center of this revolution. He is the center of the universe. He is Spartacus."

Despite this, though, McAvoy shared that Lord Asriel will struggle with the idea that his daughter could better him despite all of his efforts to be the hero of the story.

The Split actor said: "There's this whole other whispering, nagging thing that his daughter is Eve, that she's prophesized to be the revolutionary icon but it's going to be some mythological, quasi-biblical rebooting of the universe revolution and it just sounds too mystical, and he can't even countenance it.

"But to be honest with you, I think he's just feeling jealous that his daughter is stealing his thunder, and I think, weirdly, in this big, massive fantastical thing that is a parental issue for some people.

"The jealousy of the vibrancy, the vitality of their little children who've got more life in them, they're more alive and they've still got imagination and are still interesting, they're still there.

"They're capable of more, the possibilities for them are greater, and there's a jealousy that can come with that, and I think he's definitely suffering from that."

His Dark Materials Season 3 premieres with its first two episodes on Monday, December 5 on HBO at 9 p.m. ET.