The Flash: Five Things You Should Know About "Welcome to Earth-2"

Tonight's episode of The Flash will be one that fans talk about for a long time.

There's twists and turns in the story, there's cameos galore, and there's the simple fact that this is the first time our heroes have spent time on Earth-2 (while, of course, the powerless Jay Garrick is stuck back on Earth-1 with Caitlin).

Longtime DC fans will be rewarded and are going to love it. And we thought they might like a little preview of what's to come...!

How does the multiverse work?

Just how does the multiverse work on The Flash? Well, we get a little bit of a hint tonight. In the course of Barry's trip to Earth-2, fans learn something about the mechanics of the multiverse...maybe even something that could give clues as to how The Flash's crossover with Supergirl might shake out, if the "Worlds Finest" theory holds.

There's a death in the family

The Flash family shrinks a little bit as Robbie Amell keeps his promise to kill off a series regular during his appearance as Deathstorm. But who? Why was that character targeted by Deathstorm? And what will the character's death mean for Barry and company going forward?

Surprise cameos

There are cameo appearances by Earth-2 doppelgangers for Barry, Joe, Iris, Ronnie and Caitlin, of course...but that's not all. Expect to see some surprising familiar faces in the episode, many with an interesting twist on what makes them tick.

At least one new mystery is introduced

We still haven't got any idea who it is behind Zoom's mask, but that won't stop the writers from introducing a new mystery to keep Barry and company busy while they're visiting Earth-2. This one, introduced in the episode's final moments, seems likely to have big ramifications for next week's episode.

Cisco's power struggle

Cisco's powers seem to disproportionately deal with Earth-2...so what will that mean for him when he's actually there? Expect his journey toward the grand destiny that awaits him to take a major step or two while he's on Earth-2...but don't expect those steps to be easy for him.