Welcome to Earth-2

"So, which one of you lounge lizards is in the wrong universe?"

- Killer Frost questioning the people of Earth Two

It acts as the first half of a two-part episode.

Synopsis
Barry, Wells and Cisco journey to Earth-2 to rescue Wells' daughter, Jesse, from Zoom. Barry is stunned when he runs into Earth-2 Iris and Joe, but nothing prepares him for meeting Killer Frost and Deathstorm. Meanwhile, back on Earth-1, Jay has to take over the Flash's responsibilities when a meta-human nicknamed Geomancer attacks Central City.

Plot
Before heading to Earth Two, Barry closes all but one of the breaches so that Zoom has no other way to travel between the parallel Earths. Using the last breach at S.T.A.R. Labs, Barry, Cisco, and Dr. Wells travel to Earth Two, but there is a surge of energy that destabilizes the breach. The trio will be stuck in Earth Two until Caitlin and Jay can fix the speed cannon. Barry decides to impersonate his Earth Two self to get more information on Zoom. He later meets Iris and Joe of Earth Two and learns that Iris works for the CCPD, while Joe is a singer at a jazz bar. Barry is attacked by Earth Two's Caitlin and Ronnie Raymond, known here as Killer Frost and Deathstorm, agents of Zoom. In the attack, Joe is killed. Cisco attempts to help the police stop the pair, but is confronted by his own evil doppelgänger, "Reverb". Cisco discovers Reverb has greater power, including control over nervous systems. Barry tries to rescue him, but is stopped by Reverb and Deathstorm. Zoom arrives, kills Reverb and Deathstorm for harming the Flash, and then imprisons Barry alongside Jesse. Meanwhile, Jay reveals to Caitlin that he invented Velocity 6 on his Earth and that it is the real reason why he lost his speed and is dying.

Trivia

 * Whenever it's daytime on Earth Two, everything is tinted yellow.
 * During Barry, Cisco and Earth Two Harrison Wells' travel to Earth Two, they see several cameos in the dimension stream:
 * Alternate Green Arrow, Connor Hawke, who appeared in ​, the sixth episode of DC's Legends of Tomorrow.
 * An unnamed speedster from Earth Ninety, who has the same suit as The Flash from the 1990s CBS The Flash series, portrayed by John Wesley Shipp. The emblem of this Flash's suit is backward, much like the ones of Eobard Thawne and Zoom; this has been taken as a possible clue by some fans, but is most likely a production error (a left-right "flop").
 * The unnamed speedster will also appear in the Elseworlds crossover.
 * Supergirl from the CBS TV series Supergirl (a reference to Barry's future appearance in, the eighteenth episode of the first season of Supergirl).
 * Grodd, a former resident of Earth One deported to Earth Two by Team Flash.
 * Jonah Hex, an old west gunslinger (a reference to his future appearance in the DC's Legends of Tomorrow episode ​​).
 * Legion flight ring used by the Legion of Super-Heroes from the 30th century in the comics. The shot in question is from the Supergirl episode.
 * Once arriving on Earth Two, Cisco states "I've got a feeling we're not in Kansas anymore", referencing the quote from Dorothy Gale in the movie The Wizard of Oz.
 * Barry and Iris' telephone.png the telephone at Earth Two Barry and Iris' house, the names "Eddie", "Bruce", "Hal" and "Diana" appear as speed dial options below "Dad" and "Mom". The first name may refer to Eddie Thawne. In the comics, Bruce Wayne is the alter ego of Batman, Hal Jordan is the alter-ego of the second Green Lantern and Diana Prince is the alter ego of Wonder Woman.
 * The mural in the Earth Two Central City Police Department refers to a "A free and just society". This is a reference to the Justice Society of which Jay Garrick is a member in the comics.
 * When Cisco wonders what his doppelgänger would be like, he imagines him to be a rich inventor. Ironically in the Flashpoint timeline, Cisco himself is a rich inventor and the CEO of Ramon Industries.
 * At Jitterbugs, Joseph sings the show tunes "Where or When" and "My Funny Valentine".
 * Floyd Lawton's failed attack against Reverb is a reference to a scene from the movie Pulp Fiction.