We already know that Grant Gustin's The Flash is set to appear in the March 28 episode of Supergirl titled World’s Finest. This episode will be historic in the sense that it’s a crossover featuring superheroes from two distinct television networks, CBS and The CW.

So how does this historic crossover come about? How does Barry Allen find himself in National City? We now have a better sense, after the release of the official synopsis of the Supergirl episode. Check it out below (via Comic Book Movie)!

"World’s Finest" - Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire, in exchange for her help in finding a way to return him home.

And here's the awesome-looking official poster for the episode featuring The Flash, Supergirl, and other characters from the CBS series!

Season finale dates set for The Flash, Arrow, and Legends of Tomorrow!

The CW has announced the season finale dates for The Flash Season 2, Arrow Season 4, DC's Legends of Tomorrow Season 1, and a number of other shows. As you can see in the above image, this season of The Flash will close out on May 24, while Arrow will air its season finale episode on May 25. Legends of Tomorrow will conclude its maiden season ahead of those two on May 19.

Official Synopsis is out for The Flash Season 2 Episode 17, Flash Back!

Were you missing Rick Cosnett as Eddie Thawne, or Andy Mientus as Hartley Rathaway (aka the Pied Piper), in The Flash Season 2? If so, the official synopsis for Episode 17, gives us the good news that both of them are coming back. The episode, entitled The Flash Back, will air on March 29. Check out the synopsis here (via Comic Book):

A MOMENT IN TIME GETS BARRY ONE STEP CLOSER TO ZOOM; ANDY MIENTUS RETURNS AS HARTLEY RATHAWAY - After the shocking revelation that Zoom is Jay Garrick (Teddy Sears), Barry (Grant Gustin) is more determined than ever to get back to Earth-2 to stop Zoom forever. Desperate to find a way to increase his speed, Barry decides to travel back in time and masquerade as his earlier self in order to get his arch-nemesis, Dr. Harrison Wells/Eobard Thawne (Tom Cavanagh), to teach him how to run faster. However, things don't go as planned and Barry is stunned to face familiar foe Hartley Rathaway (guest star Andy Mientus), as well as old friend Eddie Thawne (guest star Rick Cosnett). Iris (Candice Patton) makes peace with her past in order to embrace her future.

Stills from The Flash Season 2 episode, Trajectory, released!

With its first female speedster set to be introduced, The Flash Season 2 is coming back on March 22. The episode is titled after the name of the villainous speedster, Trajectory. We've already got the official synopsis and extended trailer for the episode. Now, the CW has released a bunch of stills showing Trajectory’s break-in at S.T.A.R. Labs:

Share your thoughts on these updates on The Flash, and stay tuned for more!