Is Arrow about to destroy everything it holds dear?

Wednesday's season finale picks up after Oliver (Stephen Amell) left his friends to die in a cell in Ra's al Ghul's (Matt Nable) Nanda Parbat prison. Ra's plans to release a toxin and destroy Starling City, and in order to stop him, Oliver has played along with the plan. Secretly, he's been working with Merlyn (John Barrowman) to put a stop to it.

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The season has already dismantled the Arrow lair and seen Sara (Caity Lotz) and Roy (Colton Haynes) exit the series. Though the CW series is coming back for season four, executive producer Marc Guggenheim says the episode has the feel of a series finale and that its conclusion will leave viewers asking, "How can the show go on?"

In a chat with The Hollywood Reporter, Guggenheim weighs in on the finale's big events, the Flash's (Grant Gustin ) role in the episode, and how it ties into the upcoming spinoff DC's Legends of Tomorrow.

How much does the finale tease season four?

It gives you a very definitive end. It does feel like a series finale. At the same time, now that we're working on season four, there are plot threads and notions from the season finale that get pulled into season four. It really does function on both levels, much more so than previous season finales. We've never ended a season the way we're ending this season, where literally you are going, "How can the show go on?" At the end of season one in the wake of Tommy's [Colin Donnell] death, there was a question of how can Oliver go on? But there was no question of how the show was going to be the show. Here, literally there is no more Arrow identity. There is no more lair. Relationships are fractured. All the things that sort of make the show the show are kind of gone. It's an interesting conundrum the finale poses, which is, "OK, that was a really satisfying ending, but I know there is a season four, so how is there going to be a season four?" It's a cliffhanger.

What were your main goals going into this finale?

Sticking the landing on all the plot twists that have brought us to this point. This has probably been one of our twistier ends of the year. And making sure that everything came to a satisfying conclusion was definitely priority number one. We wanted to make it a big, compelling season finale. At the same time we wanted to make sure we weren't just repeating ourselves. At the end of the day, I always joke that Act V, or in the case of season one, Act VI, is going to involve Oliver punching the big bad of the year somewhere. Beyond that, how can we mix things up? How can we keep it from feeling like the season finales of years past?

See more Behind the Scenes of the CW's 'Arrow'

Oliver appears to have left his friends to die last episode. Can those relationships be salvaged?

One of the things Oliver says to Ra's in [episode] 322 is, "I've left my entire life in tatters and I basically don't have a home to go back to." In the season finale, we will learn why Oliver did that. Not just the plot reason. Someone is going to very pointedly ask him, "How did you expect to repair all of this?" Oliver will have a very specific answer to that question.

How do you work Barry Allen into the episode without having him solve all of Oliver's problems?

That's one of the things we talk about a lot, having a shared superhero universe: Why doesn't Team Arrow just call Barry all the time? That question gets answered pretty specifically in the season finale. We wrote it in close consultation with the Flash writers, knowing where Barry was in his story, and if you watch episode 23 of Arrow with 23 of Flash back to back, Barry goes straight from Arrow into the season finale of Flash. There's a pretty good explanation in the Flash story as why he can't just solve all of Oliver's problems in five minutes.

What's it like saying goodbye to Ra's as the big bad and to Matt Nable?

It's tough. Matt is a great actor and he's just a wonderful human being. I was just emailing with him the other day. We have ideas for how to bring him back next year. At the same time, if we do our job correctly, by the end of the season you feel like, "OK, I've gotten to the point where I'm narratively satisfied with the story that was told." With Arrow, nothing is ever permanent. Things are always subject to change and evolution. John Barrowman was the big bad of season one. Now look, he is a series regular on the show. Nothing is ever forever. We are just telling the end of this particular story with respect to Ra's.

Did knowing you have a spinoff coming affect the choices you made with this finale?

Not really. Ray's [Brandon Routh] last scene, which is a very definitive sendoff, was actually something we talked about way back at the beginning of the year, long before the spinoff was discussed. While Ray's sendoff does a nice job of teeing up where he is headed in the spinoff, it was always something we were going to do. It functions both as an end to Ray's story in season three, as well as a little tease of what people might be able to expect from the spinoff.

Stay tuned to The Live Feed for more from the Arrow finale.

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