The Flash is back tonight for the second half of its season, and with the show's new graphic-novel approach to storytelling, the horror of mad scientist Bloodwork (Sendhil Ramamurthy) is behind us and a new threat is shaping up.

But at the same time as Iris (Candice Patton) and her colleagues at The Citizen contend with the fallout from their investigation into a shady tech firm, the S.T.A.R. Labs gang must deal with the emotional aftermath of the Crisis on Infinite Earths crossover.

Here, showrunner Eric Wallace opens up about bringing in some backup to help Barry (Grant Gustin) handle the loss of Oliver Queen, whether Graphic Novel No. 2 includes a West-Allen baby and what we can expect from our favorite Central City reporter going forward.

Did you get to at least decompress after the crossover or did you guys go right into this episode?

Eric Wallace: We did, we were right into it. And it's funny. From a production standpoint, the crossovers affect the episodes before it and the one after it. Anyone who's in the crossover, which was Iris, Barry, Elongated Man (Hartley Sawyer) and Frost (Danielle Panabaker), they all get taken away from you to go work on Crisis, which turns out to be a blessing for us because when we were looking at episode 10.

We said, "Well Grant is so busy on Crisis, what kind of a story do we need to tell?" And one of the things we wanted to do in 610 was that we wanted to tell Team Citizen-centric story right out of the gate to tell our audience, "Hey, remember in 607, that great shot where we pushed in on Kamilla (Victoria Park), Iris and Allegra (Kayla Compton)?" We visually stated who Team Citizen was right there and we needed to follow that up and let folks know that this is the real deal. Team Citizen now is as important as Team Flash, which by the way, is one of the themes that run through a lot of the early episodes in this Graphic Novel No. 2.

It's great how the episode gives so many characters on the canvas something really important to do. It fills in a lot of the blanks with Allegra, it gives Carlos Valdes some great stuff...his post-Crisis survivor's guilt is just heartbreaking.

And his survivor's guilt will continue.

Related to that, there is also a moment where Cisco talks about how only one Earth was reborn.

I know! And then what did we see at the end of hour five?

So he's just under the impression that there's only one of them?

Correct! As is all of Team Flash. They're unaware of the existence of those other worlds. That's the question: When will they find out? Sounds like a story to me! [Laughs] They won't find out anytime soon.

See Also We Have Questions! Marc Guggenheim on the 'Crisis' Cameo & Casualty The EP talks last night's big death (why now?!), how that cameo came to be, and what's in store for Emily Bett Rickards' return.

OK, I dig it. Now, you established the existence of McCulloch Tech during the DeVoe and Cicada storylines and now it's back. The fact that you revisit it, it seems like Crisis has allowed you to take some of the seeds you planted earlier and play with them in a different way.

You're absolutely right. And some of these seeds that we planted were planted all way back at the end of Season 5. You'll be surprised at how many things pay off, how long we've actually been thinking about this. It's really nice.

And the episode ends on a cliffhanger involving Iris...

Oh yeah. And don't worry. I don't like keeping an audience in suspense. So just tune in for episode 610, you'll find out. We're not going to keep people waiting forever. I don't think that's fair. I never think that's fair.

However, it's surely going to leave an impact on whatever happens going forward?

Exactly. What I love about our Graphic Novel No. 2 is that this is really a huge Barry-Iris season coming up in this back half. And that's not to the exclusion of all other heroes, obviously. We're going to start to see a nice kind of big sister-little sister relationship with Frost and Allegra that kind of grows. We're really excited about that.

And we'll see some returning villains from the very distant past of The Flash who are coming back in new forms, as we've hinted at the season opener. You know, we need to pay that off. You will actually see some of those people. Who, I'm not saying. [Laughs]

Obviously, so fresh off of Crisis, these people are all dealing with the trauma of losing Oliver Queen (Stephen Amell). You have Diggle (David Ramsey) play an important role in Barry's grieving process tonight and, very much like in real life, it was so comforting to see a familiar face who shared that loss come around to help with the transition.

Agreed. Agreed. And it was a conscious effort on our part to honor the mothership, Arrow, the show that started at all. It was very important that our first episode back after Crisis, we had to not just address Oliver's death, but honor it in a Flash-unique way. And that meant bringing in Ollie's brother, as he said in Crisis. "I'm your brother, I'm there for you." So we were delighted to have David come over and I hope he comes back more, quite frankly. I love him. Love the character, too.

And now you're doing this Graphic Novel approach to your season, you had the Bloodwork storyline in No. 1. Do you have a name for this new season's graphic novel idea?

I do and I cannot tell you it, as it is too spoilery. [Laughs] I can now reveal that the title of Graphic Novel No. 1 in the front half was "Blood and Truth." That was the name of it. I always have to know thematically where we're driving to and as we saw in the first eight episodes, the "Blood" refers directly to Bloodwork, and the "Truth" is that Barry and Ramsey (Sendhil Ramamurthy) are going through the same thing, they're both facing death.

Eventually there will come a point in this season where I think I'll be able to reveal what the title is of Graphic Novel No. 2 and then it will be very obvious what that means. And as we're now starting to think about future seasons, each Graphic Novel will have its own title. It just won't be released immediately because of spoilers.

So the plan is to stick with this format for ongoing seasons?

Correct. This is the new format.

Great. Now, what else should we expect to see as we get deeper into this Graphic Novel? Because Iris is amazing in this episode. We've always known how great Candice is, but getting to see her doing this Deep Throat stuff, meeting sources in a parking garage and really being a boss. This is going to continue, right?

Oh yes. Boy, are you going to love next week's episode! One of I think the funniest, coolest, Iris scenes we've done so far is in that episode. And again, no spoilers, but Iris' strengths will continue throughout this season and as a result of what's going on with her...let me just say, the first graphic novel, "Blood and Truth," even thought it was an Iris-Barry story, it was very Barry-centric. In this Graphic Novel No. 2, it's Barry-Iris, but it's more Iris-centric. And that's on purpose so that we can balance the two of them out...at the end of [this arc], no matter what they go through this season, Barry and Iris will end the season closer than ever before. And I mean by far because they're going to some crazy places.

Would any of those places result in a pregnancy?

Well I will tell you that right now, no pregnancy this season. Not happening.

Fine. Is Eric Nenninger, your Big Bad in this episode, sticking around?

Oh yeah, we love him. He is a delightful bad guy. I think you're really going to enjoy some of his scenes. They're pretty great and he's just a villain you love to hate.

That's because he's handsome and smug and we want to destroy him!

I know, it's like no one should be that good looking, stop that! We must bring him down! [Laughs]

And post-Crisis, what's Barry's next big challenge?

Barry's next big challenge is learning to be the leader. Oliver's gone and someone has to fill his mantle. So that's going to be tricky for Barry, who is kind of stepping into that role. So you'll see a little bit of that. It will also be dealing with, "Okay, I'm not going to die. How do I learn to start living again?" That's a very, very big theme for Barry in this back half. So that's going to take him on a very emotional journey.

And you know, quite frankly, we have some very hilarious episodes coming up, especially in these first few...then in the back half of the season it gets more intense.

The Flash, Tuesdays, 8/7c, The CW