The Diplomat stars preview an intense season 2: 'It raises the temperature'

"The call is coming from inside the house."

Kate Wyler (Keri Russell) utters those words in the season 2 premiere of The Diplomat, as she shares the realization that shocked fans in the season 1 finale: She believes that Prime Minister Trowbridge (Rory Kinnear) was behind the attack on his own ship. So ... what does she do now?

"Kate's pretty sure it's the prime minister, so how do you prove that when you're inside the U.K.?," showrunner Debora Cahn says. "One of the unique things about the relationship between the U.S. and the U.K. is that we share intelligence. So we have a deal that we don't spy on each other. And even if we wanted to, it would be really hard because we share everything. So how do you prove it? And then if you prove it, what the hell do you do about it? Season 1 was building relationships with people, but can you still trust them?"

As Russell says, "It raises the temperature. What's fun about this season is realizing that it might be the people closest to you who are involved in something nefarious."

And that's not even talking about the explosion that ended last season, putting multiple characters in harm's way. Thanks to a recent teaser trailer, we know Hal (Rufus Sewell) makes it out alive. "Hal comes out of this alive but so shaken," Cahn says. "Almost dying like that can shake a lot on every level."

Not to mention the fact that his wife was just about to take things to the next level with Dennison (David Gyasi) before that bomb went off. "Kate was ready for this new relationship. She was really ready to move on, and there's nothing like a near-death experience for you to just cling to somebody and forget all of the stuff that was driving you apart," Cahn says. "It was over. They had reached a conclusion, so when suddenly she's like, 'I'm back. I'm here now.' Do you trust it? Do you trust her? A lot of the season is about trust and there is a line that comes later in the season, where Kate says to Hal, 'Of course, I don't trust you. This isn't built on trust.'"

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It's a complicated relationship, to say the least. And one that confuses just about every other character on the show. "I think the people around them in the story don't know what's happening. They don't know what to make of them," Russell says of the married couple. "It's unnerving because they're fighting cats and dogs or they're completely backing each other up in this fierce way. And it's unnerving because people don't know where they stand."

But do they know where Kate stands with Dennison? And speaking of, how will he handle the realization that his country could be behind the killing of its own citizens? "We had this really interesting conversation when we were filming season 2. I felt like I was losing the essence of who this person is, and Deb had to remind me that not only is he a politician, he's also a Tory politician," David Gyasi says. "There's good and bad everywhere, but there are perhaps meetings and situations and policies that he's had to sit in that may cut him a different way. And he has constantly had to make decisions as to how do I keep doing this? And there were certain moments in season 2 where I was screaming on the inside: 'Do something!""

As for what's next for Dennison and Kate, Gyasi says the "pull" and "sizzle" of their relationship will continue. But they've both got their hands full.

Season 2 will introduce Grace Penn (Allison Janney), the vice president that they're hoping Kate will soon replace. "Grace Penn is a problematic figure on a bunch of different levels, but she certainly falls in that category of characters who will defy the expectations of the people in our story and hopefully of the audience," Cahn says. "It's important to me to be able to look at the subject matter that we're talking about in a multidimensional way. I think that we all want to look at the world and say, 'These are the good guys, and these are bad guys.' And once you really get in there, no matter where you go in the world, there's a bunch of extremely complicated people leading complicated lives just trying to make things a little bit better."

"There are a lot of corrupt politicians or evil politicians on television," Cahn continues. "And for me, it's so much more interesting to think about: What if they're not? What if they're actually good and we're still as f---ed as we are right now?"

The Diplomat season 2 premieres Oct. 31 on Netflix.