The Flash: [SPOILER] Returns, Offers New Clue About S4 Premiere Mystery

SPOILER WARNING: This article contains major spoilers for "The Elongated Knight Rises," the latest episode of The Flash.

"Crisis on Earth-X's" Mystery Girl has returned. In "The Elongated Knight Rises," the latest episode of The Flash, she bumped into Ralph Dibney and Cisco Ramon at C.C. Jitters. As they strolled away, she began to write in a notebook using the same glyphs Barry had written in right after he was pulled out of the Speed Force in the Season 4 premiere.

As the episode drew to a close, Ralph and Cisco went to grab coffee together. However, when it came time to pay, neither one had money on them. They went back and forth over what to do, only for Mystery Girl to step in. She slammed a couple dollars onto the counter, then rattled of a spiel about paying it forward.

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Ralph and Cisco were a little perplexed by her rant, but nodded along until she was done. As she returned to her table, they exchanged looks and walked out. Mystery Girl watched them go, then went back to her notebook. The camera zoomed in on the book, which revealed the glyph-like writing.

This same writing appeared in the Season 4 premiere. When Barry returned from his six month stay in the Speed Force, he spoke only in gibberish phrases and obsessively wrote across any surface in front of him in an as-yet-undiscovered language, as in the photo below. Cisco began to piece together the meanings behind these glyphs, though they seemed to turn up similarly nonsensical phrases.

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During “Crisis on Earth-X,” Barry Allen met the same young woman just moments before his marriage ceremony. The woman, a caterer at the event, was awestruck at meeting him. She insisted that he say “I do” and even called the wedding “one for the ages.” Despite her big scene, the character did not return during the crossover event and has not been seen on The Flash until now.

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Though Mystery Girl has not yet received a name on the show, that hasn’t stopped fans from speculating about who she is. The prevailing theory is that she is playing Dawn Allen, Barry and Iris’ daughter. Dawn is also one of the Tornado Twins, a pair of superheroes from the future. Another theory speculates she is playing Jenni Ognats, Barry’s granddaughter and future superhero.

If Mystery Girl is indeed Dawn Allen or Jenni Ognats, that means she hails from the future. As such, the language she was seen writing in -- a commonality she shares with Barry -- may also be of the future. Seeing as the comic book version of the "Trial of Flash" storyline ended up with Barry retiring in the 30th century, this writing could indicate that the show will head to the future sometime soon.

Airing Tuesdays at 8 pm ET/PT on The CW, The Flash stars Grant Gustin as Barry Allen, Carlos Valdes as Cisco Ramon, Danielle Panabaker as Caitlin Snow, Candice Patton as Iris West, Jesse L. Martin as Joe West, with guest appearances from Keiynan Lonsdale as Wally West and Hartley Sawyer as the Elongated Man.

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