It’s the question that’s been plaguing fans of the The Flash for months: Who the heck is the Mystery Girl?
Played by Jessica Parker Kennedy, the Mystery Girl made her debut in the crossover event Crisis on Earth-X, where she was an overly excited waitress at the wedding of Barry (Grant Gustin) and Iris (Candice Patton). Her appearance sparked theories that she could be their future daughter, Dawn Allen, or even their granddaughter, Jenni Ognats, a.k.a XS, who is also a member of the Legion of Super-Heroes. Good news: We’ll be getting answers soon!
“You get the question answered as to who she is,” executive producer Todd Helbing tells EW of the upcoming season 4 finale. “There’s actually an extra little bonus where something happens where you’ll realize exactly how she’ll play a part in the future.”
Her identity actually plays into one of the two big cliffhangers closing out the season — the other setting up a new threat for season 5. “I’ve known since before we started this season,” Gustin says of her identity. “It’s been the thing that I’ve been most excited about all season, which sounds ridiculous because it’s really a season 5 thing. I’ve spent all of season 4 being excited about this thing that we’re going to do in season 5!”
Since Mystery Girl’s crossover debut, she’s popped at least twice more, the first of which saw her scribbling in a journal the same symbols Barry used upon exiting the Speed Force. But the teases go even further back than fans realize. “It’ll be one of the cooler reveals that we’ve done in a couple seasons,” Gustin says.
Mystery Girl’s latest appearance back in episode 15, however, left some fans (and cast members!) scratching their heads. Though she was as chipper as the her past run-ins with Team Flash, Mystery Girl’s mood swiftly turned somber after crossing paths with Caitlin (Danielle Panabaker) and Harry (Tom Cavanagh), possibly signaling some future animosity toward either, or both. “I will actually say, I know who she is and a little bit about her backstory, and how she’s connected to a handful of characters,” Gustin notes. “But I didn’t know what that was when I watched that episode. I was like, ‘Huh, I wonder what that’s about.’”
Panabaker was also surprised by Mystery Girl’s ominous look at the end of the hour. “That, to me, is actually the fun of watching our show sometimes, because what I read on the page is not necessarily the way things end up cut together,” Panabaker says. “Harry and Caitlin leave the scene and then there’s the push-in on the Mystery Girl, and when I watched the show I was like, ‘Oh, that’s a very different look than she gave me the rest of the scene. What does it mean?!’”
The Flash airs Tuesdays at 8 p.m. ET on the CW.