Arrow type TV Show network The CW genre Superhero

Comic book fans’ dreams are about to come true when two superheroes face off—no, we’re not talking about Batman v Superman: Dawn of Justice. Arrow‘s emerald archer and The Flash‘s scarlet speedster will face off during an epic two-hour, two-night crossover event.

But why, oh why, would allies Barry Allen (Grant Gustin) and Oliver Queen (Stephen Amell) go toe-to-toe? You can thank comic book villain Roy G. Bivolo (Paul Anthony) for that. To get the scoop on the crossover event, EW caught up with executive producers Marc Guggenheim and Andrew Kreisberg:

ENTERTAINMENT WEEKLY: What brings Team Arrow over to Central City?

ANDREW KREISBERG: A mysterious man who kills someone with a boomerang is what brings them to Central City, but they then get caught up with Barry’s latest metahuman investigation of Roy G. Bivolo, who is robbing banks by inducing uncontrollable rage in the patrons of the bank. At first, Oliver is not too keen on helping Barry with his investigation, but pretty soon he and Felicity (Emily Bett Rickards) and Dig (David Ramsey) get swept up in it.

How does Team Arrow react to seeing these metahumans?

MARC GUGGENHEIM: For my money, the best reaction goes to Dig. His reaction, which really comes in The Flash part of the crossover, is just priceless.

We get to see Flash and Arrow fight because of Roy G. Bivolo. What can you tease about this epic showdown?

Kreisberg: When Greg Berlanti and I were trying to figure out this story, we were thinking, “What’s the coolest thing we could see them do?” We were trying to figure out all these ways they could team up and we hit on this idea of the old Comic-Con argument, where people would sit around and say, “Who would win in a fight? Superman or the Hulk? Could Batman beat Wolverine?” When we started talking about it like that, it became clear that the funniest thing we could do would be to have them actually fight each other and have Dig, Felicity, Cisco (Carlos Valdes) and Caitlin (Danielle Panabaker) have those arguments on who would win the fight, The Flash or the Arrow, actually be part of the show.

Meanwhile, Eddie (Rick Cosnett) is apparently starting a task force to go after The Flash. Does the Arrow fall into his cross hairs as well?

Kreisberg: The best special episodes—especially when you think back to “Once More, with Feeling” on Buffy—are not just gimmicks, they also really enhance the plot and the character arcs. This episode really does that, especially where Eddie is concerned. It all comes out in this episode that Iris (Candice Patton) has started a correspondence with The Flash that has turned into them meeting together, which is not something that Eddie approves of. The events of this episode, both the Arrow showing up and The Flash getting whammied, only increase Eddie’s desire to see The Flash unmasked and brought down.

How long can Barry feasibly keep this secret from Iris?

Kreisberg: As long as we’re getting story out of his keeping this secret from her, it’s good. We’ve learned with Arrow that the sooner people find out about the hero’s identity, it opened up all new storylines that you can tell with these people. I suspect she’ll find out sooner rather than later.

How are Caitlin and Cisco dealing with this whole new team in S.T.A.R. Labs?

Kreisberg: Caitlin is thrilled because she and Felicity have struck up a friendship. There’s a great line in the episode where Caitlin and Felicity are talking science and Caitlin just says, “It’s so nice to have another woman to talk to.” Cisco is over the moon. He’s as much as fanboy as Barry is, so the fact that the Arrow is in town and he gets to find out who the Arrow is, it’s his dream come true.

How does Wells (Tom Cavanagh) feel about the Arrow?

Kreisberg: What’s interesting in this episode is that Joe (Jesse L. Martin) and Wells, who normally have a tension between them, are actually in complete agreement that the Arrow is bad news and should leave town as soon as possible. So much of these two episodes are really examining the very different kinds of heroes that Barry and Oliver have become. Joe and Wells share this view that the Arrow is dangerous and unstable and not the kind of hero that Barry should be emulating. What’s interesting about these episodes is that they’re both validated in some ways, but Oliver actually really learns something through the course of these episodes. He grows from them, too, so it’s really special that these shows can speak to each other in that way. As much as we’ve seen so far in the series that Oliver’s had a tremendous impact on Barry’s life, we’re also seeing that Barry has had an impact on Oliver’s life as well.

Now, for the second half of the crossover. What brings Team Flash to Starling City?

Guggenheim: They are tasked with helping catch Canary’s (Caity Lotz) killer at the end of the first part of the crossover. We’re immersing them deeply into our season-long mythology.

Captain Boomerang (Nick E. Tarabay) will be stirring up trouble, particularly targeting Lyla (Audrey Marie Anderson). What can you tease?

Guggenheim: We’re always saying that we want the stakes on Arrow to be high, particularly for an important episode like this one. We always find that the stakes are highest when people or characters that we care about are placed in jeopardy. The city is certainly placed in jeopardy, but we wanted to personalize it in the form of Lyla, who is a fan-favorite character and certainly a favorite character of Diggle’s.

How does Team Flash handle the darker side of being a hero?

Guggenheim: With the Arrow part of the crossover, I was a bit more interested—since we got the Team Arrow reaction to metahumans in The Flash episode—to explore what is Team Flash’s reaction to the darkness of Starling City and the darkness of the world that Oliver inhabits. It’s very, very different from the world that Barry and his team deal with.

Kreisberg: Somebody in the Arrow universe gets fairly badly hurt in the Arrow episode and we see Caitlin dive in as a doctor. One of the things that we talked about a lot is the idea that on The Flash, she’s a fun doctor, but our tone note for that was to treat it like ER and have blood everywhere and have Caitlin be shaken up. One of the things Caitlin and Cisco realize in the Arrow episode is they’ve been having a lot of fun, despite being scared in dangerous situations, but the world of the Arrow is a darker, bleaker world. It takes a different kind of fortitude to survive it.

As opposed to how Oliver helps over on The Flash, what makes Barry coming over to Arrow different?

Guggenheim: It’s so different from the first hour. The episode of Flash really feels like an episode of Flash, and the episode of Arrow really feels like an episode of Arrow. It’s an opportunity for us to look at our characters through a completely different light. We’re basically getting a chance to look at Oliver through Barry’s eyes. It’s a different perspective than the one we’ve typically seen with our Team Arrow. They’ve all figured out their opinions of Oliver for the most part, but things are going to be pretty testy between Oliver and Barry, because Barry is going to have some very strong opinions as to how Oliver does his business in Starling City.

There’s been word that a big secret of Oliver’s is revealed on The Flash. What came with the decision to reveal a big secret about him on a different show?

Guggenheim: Once you see it, you’ll completely understand. It’ll make a whole lot of sense.

The Flash and Arrow crossover event kicks off Tuesday at 8 p.m. ET, continuing Wednesday at 8 p.m. ET on The CW.