The CW says of “Welcome To Earth 2”:
Barry, Wells and Cisco travel to Earth-2 to rescue Wells' daughter from Zoom, and encounter Killer Frost and Deathstorm. Meanwhile, back on Earth-1, Jay takes over the Flash's duties when a meta-human nicknamed Geomancer attacks Central City.
Longtime talkbacker Shermdawg recaps last week’s “Fast Lane”:
On the night of the particle accelerator explosion some poor schmuck who owed money is dropped into a vat of tar and turned into a half man-half tar metahuman which Cisco later dubs "Tarpit" when he begins seeking revenge on those that did him wrong.
It just so happens the last person on Tarpit's shit list is the same man Iris West threatens with a tell-all expose if he doesn't leave town. That person being the man setting up Wally's races which he had once took part in to pay his mother's medical expenses, but in light of her passing, Iris felt as though he didn't need to continue risking his life, and became increasingly frustrated with Joe when he wouldn't step in as he felt it would push him away.
Once she finally manages to sway Joe into doing something, they pick the wrong time to approach Wally as Tarpit also shows up at his latest race, ruining it....and sending Wally's car hurling through the air. Luckily Barry is alerted and arrives just in time to pull Wally from the vehicle mid-air, and push Tarpit's target out of the path of the car, but as it crashes to the ground a shard of glass lands in Iris' shoulder when he fails to catch up to it as a portion of his speed force had been drained by a device Earth-2's Harrison Well's secretly implanted in his suit.
Something Wells had been forced into doing by Zoom to ensure his daughter's safety. After wrestling with the guilt of his betrayal, Iris' injury finally pushes him into confessing what he had done. This sends Joe into a rage knocking him out and tossing him in a containment cell.
After Team Flash defeats Tarpit (who turns into a Clayface-like monstrosity in his final scene) they discuss what do with Wells, who suggests sending him back to Earth-2 and sealing all of the breaches behind him after they discovered the means to do so earlier in the episode. Barry however, manages to convince Joe and the others to forgive him when he makes the point that they would likely be forced into making the same decision if one of their loved ones were in danger. Upon his release, Barry tells Wells he's proven he's part of their group and they would assist him however they could back on Earth-2 hopefully finding a way to rescue his daughter from the clutches of the evil Zoom.
