Supergirl-Flash crossover heading to CBS

The Flash‘s Barry Allen is heading to National City!

Supergirl will stage a crossover with The Flash when Grant Gustin appears as the Scarlet Speedster on the upcoming March 28 episode of the CBS super series, EW has learned.

Details on the episode are being kept under wraps. There’s also no word yet on whether Melissa Benoist will return the favor and appear on The Flash. However, here’s why this crossover is important: If Barry Allen can make his way to National City, that means so too can Oliver Queen (Stephen Amell) in the future.

Though the Emerald Archer is missing from this initial outing, having The Flash first crossover with Supergirl seems a little more plausible considering they’re both metahuman and superhero-heavy shows. But since Barry Allen lives in a neighboring town to Oliver Queen, that means that Kara Danvers (Benoist) hails from the same universe. Therefore, the possibility for a future crossover with Arrow isn’t improbable — it’s just not happening right now.

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“We are so incredibly excited to announce something that we have dreamed of happening since we starting making Supergirl —The Flash and Supergirl are teaming up!” said The Flash and Supergirl executive producers Greg Berlanti and Andrew Kreisberg. “We want to thank Grant Gustin for making the time to come visit (on top of his already immense workload) and all of the folks at CBS, The CW, Warner Bros., and DC for working this out. And finally thanks to the fans and journalists who have kept asking for this to happen. It is our pleasure and hope to create an episode worthy of everyone’s enthusiasm and support.”

Fans of the Berlanti-verse have basically been expecting some form of crossover ever since Supergirl was first announced, especially because The CW super shows have a knack for hosting an annual event that brings the superheroes together — this year’s even included new series DC’s Legends of Tomorrow. That possibility hit fever pitch at the Television Critics Association’s winter press tour last month when Berlanti said the crossover would need to be locked down soon.

“I would love it, a lot of things would have to go right and people would have to say yes,” Berlanti said. “It would have to figured out very soon. It would all have to be figured out in the next month or so. As it remains right now, we’ve talked internally about how cool it would be, but we haven’t had official conversations. [The CW chief Mark Pedowitz] is supportive.”

Supergirl airs Mondays at 8 p.m. ET on CBS, while The Flash airs Tuesdays at 8 p.m. ET on The CW.