'Arrow' On The CW: Marc Guggenheim Previews 'The Undertaking' And The 'Epic' Season Finale

Tonight's "Arrow" (8 p.m. ET on The CW) will reveal exactly what "The Undertaking" is -- and we're guessing it's nothing good, since it's masterminded by the decidedly scary Malcolm Merlyn (John Barrowman).

And, since Oliver (Stephen Amell) and Diggle (David Ramsey) took a break from their bromance last week, Oliver will be relying on Felicity (Emily Bett Rickards) in her first solo mission, which Rickards described as "extremely dangerous."

For more intel on the final three episodes of the season, The Huffington Post spoke with executive producer Marc Guggenheim, who had plenty to say about tonight's episode, Felicity's new role, Tommy's relationship with his father and the "epic" season finale. Read on for much more.

What can you reveal about Felicity's first solo mission in the field in "The Undertaking"?
It’s so much fun. When we brought Felicity into the "Arrow" circle of trust, I think everyone thought that she’d just be standing in the way or looking at computer screens. But for us, one of the fun things is taking the fish out of water approach to her and giving the audience a chance to see her out in the field. That actually happens in [Episodes] 21 and 22. It’s winning because she brings her surprise sex appeal in Episode 21 and she brings her think-on-her-feet wittiness to bear in Episode 22. She’s a pretty effective field operative, much to her own surprise. It’s fun to watch her get caught in some tricky situations and have to talk her way out of them. I think it creates some of our best moments. I have to say, we’re ending the season with our strongest episodes -- not just for Felicity, but for the entire cast. Everyone really is cooking with gas by the end. It’s fun to see everyone finding new gears.

Roy Harper (Colton Haynes) is a little bit obsessed with finding The Hood. Is it a case of just wanting to thank his savior, or does he feel -- misguidedly or not -- that he has something to offer the vigilante in return?
That’s actually something that we are going to be slowly revealing over the last four episodes of the season. But you’ll learn in Episode 22 the real reason why finding The Hood is so important to him. We certainly lay the foundation for that in Episode 20. Episode 20 is the first episode after his important encounter with The Hood in the subway in Episode 18. So, we’re telling like this little three-part story that really reaches its climax in part four, which is our season finale, Episode 23 ... The best stuff really is yet to come as far as Roy’s concerned.

How will we see Tommy (Colin Donnell) and Malcolm's relationship evolving in the final episodes? It seems like they're on the way to establishing the kind of bond Tommy always wanted, which is actually now a very bad thing.
That’s really the thing. One of the things that we’re doing, and we certainly started at the end of Episode 19 when Tommy went to go work for his dad, is bring him and his father closer and closer together. Tommy’s redemption over the course of the season and then his potential fall from grace at the end of the season, I think is a big piece of the fuel that fuels these final episodes. It obviously all is bound up in this love triangle between him, Oliver and Laurel (Katie Cassidy). So, everything’s kind of related. As Tommy’s father’s plan begins to approach fruition, Tommy is getting closer and closer to his father. Then the question becomes: Whose side will he ultimately be on? There’s a great exchange between Oliver and Tommy in the penultimate episode of the season where Oliver says, “What do you do here at your dad’s company?” And Tommy, in a really nice line read by Colin Donnell says, “I work very closely with my father.”

So ominous!
It’s very ominous. That’s exactly the word. That’s a lot of fun because I think the fans are sort of aware of what Tommy’s trajectory is. We’re looking forward to revealing to the audience how that is all going to play out.

What can you preview about the finale itself?
I’ll tell you, it’s really epic. The episode is huge. I was just up on set and even I was like, "Oh my God, what are we doing?" It looks like a movie. It’s a completely new level of production value, which I think for this show is really saying something. Basically, everything that we’ve been working up towards since the pilot, it all comes to a head. Oliver, Tommy and Laurel; Tommy’s dad; Tommy’s choice -- does he choose to join with his dad or join with Oliver? Moira (Susanna Thompson) and her relationship with her children as all of her demons come to light. It is a jam-packed episode. That’s just the present day stuff. We’re also building to an epic finale with the stuff on the island and the flashbacks and we’re leading up to a big, iconic moment in Oliver’s journey from Oliver Queen to being the Arrow. So, there’s just a huge number of things going on and things happening in that episode. We were just talking about how to bring it all in under 42 minutes. It’s going to be a very, I think, satisfying finale for everyone. In many ways, Episode 22 is a satisfying finale. We said that 22 is our season finale and 23 is finale plus.

Will we see any familiar faces from earlier in the season in the finale?
Actually, we’re bringing back both Hilton, played by Roger Cross, and Joanna, played by Annie Ilonzeh. So it really is this feeling like the gang is all here. We tried to bring back as many cast members who you’ve seen in the course of the first season that would fit into the story. It’s designed to be a very satisfying season finale. There’s an art, I believe, to constructing a good and satisfying season finale of a show. It’s part cliffhanger and part resolution. You want to strike the right balance between both of those things. Enough that you feel like you’ve gotten, "This is what Season 1 has been about and I understand the answers to all these questions." Then of course all the little things that make you lean in to want to watch Season 2.

"Arrow" airs Wednesdays at 8 p.m. ET on The CW.