Welcome to Earth-2
Earth-2 is a wacky place. Harry, Barry, and Cisco close all the breaches except for the one in STAR Labs and take off together to Earth-2. This overloads the speed canon, which puts them all in danger of being trapped on Earth-2 forever unless Jay can fix the canon. Meanwhile, Barry immediately gets caught up in Earth-2’s strangeness, despite Harry’s warning to stay neutral. Barry kidnaps Barry-2 and takes his place in order to discover Zoom’s location, but instead comes to learn that Barry-2 is married to Detective Iris West whose partner is an inept Deadshot and whose dad is a lounge singer (because why not put Jesse L. Martin’s beautiful crooning to good use). Caitlin is the meta-human villain Killer Frost while Ronnie is her partner Deathstorm who both work for Cisco’s doppelgänger Reverb, who in turn works for Zoom. Things get crazy as Killer Frost and Deathstorm root out the breacher Barry and Joe gets caught in the crossfire, dying in the process. Meanwhile, Harry seems to be the only one on task as he reasons with Barry to leave his Earth-2 family alone and get back to finding Zoom. In the end, Barry gets kidnapped by Zoom who promises that his prison is the last room he’ll ever see.
Earth-1
While Barry is gone, Joe has to deal with a meta-human called the Geomancer who is determined to take on the Flash. With Barry away on Earth-2, Joe has to figure out how to stop Geomancer without his usual backup. Meanwhile, we learn that Zoom didn’t take Jay’s speed after all, that he lost his speed while abusing the speed drug Velocity Six. Caitlin is able to improve upon the formula, making it safe though not incredibly long lasting. Jay regains is speed long enough to help Joe and stop Geomancer. While Caitlin considers the steps towards Velocity Eight, Jay turns his attention toward fixing the speed canon.
Barry
I can see how Barry might get caught up in his doppelgänger’s life, especially when Iris is his wife and his mother is still alive – however, Barry really seems to have the shortest attention span in the world. He’s there for a very important and specific mission – which, if he doesn’t complete in a limited amount of time, means he’s trapped on Earth-2 forever – so you would think that he could focus for just a second on the task at hand. And for someone who takes responsibility for the slightest of harm that comes to anyone he knows, the fact that his very presence with his Earth-2 family caused Joe West’s death doesn’t deter him in the least from remaining with Iris. I think someone needs to get some perspective.
Cisco
Coming face to face with his Earth-2 doppelgänger, Cisco learns that he has experienced only the very tip of his powers. Reverb tells Cisco that together they could defeat Zoom and rule Earth-2, also telling Killing Frost that he could shatter her nervous system with the barest of effort. Reverb offers Cisco a place by his side, causing Cisco to use a Star Wars reference (“Are you Cloud-City-Vadering me right now?”) followed almost immediately by a mixed Star Trek/Star Wars reference (“Listen Mirror-Mirror, I already told you I’m not turning to the dark side.”) Things must be pretty serious. In the end, Zoom kills Deathstorm and Reverb, leaving Killer Frost, Iris, and Cisco floundering as Barry is kidnapped.