"Arrow" and "The Flash" have made great use of the fact that they exist in a shared universe. Supporting characters from "Arrow" have appeared on "The Flash" since nearly the beginning of the CW series' freshman season. The shows also enjoyed a successful two-part crossover event that featured the two titular heroes guest-starring in each other's shows. Now, as "Flash" executive producer Andrew Kreisberg revealed in an interview with Variety, the shows are poised for another meet-up.

In the "Flash" episode titled "All-Star Team-Up," Felicity Smoak (Emily Bett Rickards) and Ray Palmer (Brandon Routh) will travel to Central City to check in with Barry Allen (Grant Gustin) and his friends at STAR Labs. Kreisberg teased that this meeting will have come at just the right time for the scarlet speedster.

"In episode four of 'Flash' when Felicity came by, it wasn't just a gag to have Felicity come by," explained Kreisberg. "It really was integrated into the story. When you reach what's going on in 'The Flash' at that point in the season, Barry is really at a crossroads. Having Felicity come by exactly when he needs her really plays into the whole storyline. It's fine because as ['Arrow' executive producer] Marc [Guggenheim] said, Ray Palmer is all about technology and STAR Labs is all about technology. We get to see Ray so happy to be in STAR Labs... With Cisco [Carlos Valdes] and Ray, they're new best friends. The STAR Labs team is going to help Ray further his ATOM project."

The episode will mark Rickards' third appearance on "The Flash"; it will be Routh's first. The episode, which will be "Flash's" eighteenth, won't air until this spring at the earliest. "The Flash" airs Tuesdays on the CW.