It's been a rough month for the good guys on The Flash. Just two weeks ago we watched them lose Killer Frost in the battle against Deathstorm, and now it seems another of the people closest to Barry Allen (Grant Gustin) has vanished yet again. So, what happened to Iris West-Allen (Candice Patton) this time, and how does Barry get her back?

Last week's episode, "Funeral for a Friend," was hard enough on the team because they had to recover from the battle with Deathstorm and mourn the loss of Frost, who Caitlin (Danielle Panabaker) is still fighting to get back in some form. Things got quite a bit more complicated at the end of the episode, which saw Iris just flat-out vanish in a flash of green light, apparently disappearing into the Still Force amid the time sickness she's struggled with since last season. 

So, what does Team Flash do now? This week's episode of the series is dubbed "Into the Still Force," so we know Barry and crew are going after her, but that leaves quite a few questions still left to answer.

Speaking to TV Line, showrunner Eric Wallace (who also directed this week's episode) outlined three major questions the show has to answer right now: Where is Iris in the Still Force? Why does this keep happening to her, and an even bigger question that sets the stage for the Season 8 endgame on the show.

“Where did this time sickness come from and who gave it to her for what reason?” Wallace asked. “That is why, even though we’re in the middle of our interlude episodes [between Graphic Novel 2 and 3], this episode really is a prelude to the final Graphic Novel of the season, and the Season 8 finale.”

But of course, Wallace also made sure to reassure fans he wasn't about to throw them yet another dark twist, at least not when it comes to Barry and Iris. 

“Of course Barry and Iris will come back together, but how? And who will they be when they get back together? But here’s the great news,” Wallace said. "As you know very well, I believe in happy endings, so I can tell people right now: this time when they get together, they will be together for the foreseeable future, living happily ever after and all those good things.”

While we can look forward to an eventual reunion for the central couple of The Flash, though, there are still dark times ahead for the meantime, particularly when it comes to Caitlin and the way she deals with the loss of Frost. How far is she willing to go to bring her sister back, and what's she willing to do?

“It all goes back to ‘Armageddon’ Part 5, and that wonderful scene between Danielle [Panabaker] and Tom Cavanagh," Wallace said. "We saw that Caitlin has a much darker side, and is willing to cross lines that we thought she’d never be able to cross, when she says, ‘I wont kill you, Reverse-Flash, but I’ll let you die.’ That was a clue to the audience that this storyline was coming. She is about to go down some very dark territory, and there will be consequences.”

"Into the Still Force" airs tonight on The CW.

Looking for more sci-fi TV? Check out shows like Resident Alien, Brave New World, Project Blue Book, Eureka, Heroes, Intergalactic, and more streaming now on Peacock. Looking ahead, SYFY has new series The Ark in the works from original Stargate film writer/producer Dean Devlin, as well as Stargate SG-1 producer Jonathan Glassner.