Previewing Arrow's "Nanda Parbat" With Marc Guggenheim, Andrew Kreisberg and John Barrowman

Tonight's episode of Arrow sees John Barrowman's Malcolm Merlyn called on the carpet for his crimes against the League of Assassins by Matt Nable's Ra's al Ghul -- and Oliver Queen and John Diggle heading to Nanda Parbat to rescue him.

During a screening of the episode earlier this week, the producers, Barrowman and actress Katrina Law joined reporters for a conversation about the episode and the show's future.

Here's what they had to say to tease tonight's episode, titled "Nanda Parbat,"  which airs tonight at 8 p.m. ET/PT on The CW.

For people who haven't seen the episode, what's the most exciting thing that's coming?

Andrew Kreisberg: We already knew what the schedule was going to be, so we already knew this episode had a big break coming. So it's designed to be a sort of crazy cliffhanger. I think that Willa has just risen to such amazing heights these last few episodes and continues in this one, and seeing what she's willing to do and what Oliver's willing to do for her soul. One of the things we talked about very early on was that this season is really the fight for Thea's soul and more than anything, victory this season for Oliver is saving Thea. She's caught between disparate forces.

And then seeing what happens to Merlyn after these episodes, it's just the most screwed-up family show we could possibly think of.

Marc Guggenheim: I'm really excited for people to see The Atom suit in its full glory and the first time Ray flies. That's a big moment for us in that the show is not The Flash. We don't traffic in these sort of visuals. So it was a big deal for us to get this kind of character on the show, looking the way he does and everything.

Kreisberg: Also, to finally have John [Barrowman] and Matt [Nable] in the same scene. The whole idea of Ra's al Ghul was really wish fulfillment, on our part. After John had almost been assassinated by Deadshot, and he had a little speech where he said, "I met a man and went to Nanda Parbat," we thought, "Maybe, one day, in Season 3, they'll let us have Ra's al Ghul be the villain."

John Barrowman: I remember you said to me, "We'd love to have one point where you're on your knees in front of Ra's." I don't mean that in a rude way, but you wouldn't tell me what would happen.