Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.”
― Robert Frost
The Flash usually knocks it out of the park, with fun action and great performances. The problem with this one is that this ep APPEARS to turn one of the comic's most beloved heroes, Jay Garrick, into a nasty serial killer, basically undercutting the source material and pissing on the hardcore fans.
But let's tap the brakes here - I trust that the showrunners have a plan, because if they don't, then this will be a HUGE mistake that the show may never recover from.
Anyway, the origin story for Zoom is finally revealed: Zoom is in fact Hunter Zoloman, who as a child witnessed his father murder his mother. So now we have the narrative dichotomy of Barry and Zoom. Barry witnessed his mother's murder, as did Hunter. Barry was taken in by a loving, caring family, which molded him into the hero he is today. Hunter wasn't so lucky. He was shuffled off to a horrible orphanage, and as a result became one of the most vicious serial killers on Earth 2 (23 kills and counting). He was apprehended and subjected to repeated electro-shock as punishment, until the day when Earth 2 Dr. Well's particle accelerator went kablooey and gave Hunter his super speed.
So the whole nature/nurture argument is shown by how the two men turned out. An interesting sidebar.
Back on Earth 1 Barry has, with the help of the Star Lab peeps, developed super-duper speed, 4 times the norm. He now decides that this is the time to finally get Zoom and end this. The problem is that they closed all the breaches between worlds and there's no way to get to Zoom. So what do we do about that? Enter Cisco! Barry remembers that Cisco's double on Earth 2 (the baddie Vibe) had the power over dimensions, so with the help of the special specs stolen from Vibe, Barry enlists Cisco to open a breach.
Cisco opens a tiny crack in a breach, but is overcome with guilt that he will go dark-side like his Earth 2 counterpart and stops. Barry eventually talks Cisco into it, greater good and all that.
Cisco opens the breach, and in pops Zoom. Zoom chases Barry around the city REALLY FAST (of course). They eventually make it back to Star Labs, where the crew has a little surprise for Zoom. Cutouts of Hunter's murdered mother and killer father pop up and cause Zoom to pause just enough so that Barry can trap Zoom with a leg-iron thingy.
This is when Zoom admits to posing as Jay to give people hope on Earth 2, only to snatch it away for his own evil reasons. He even went back in time to get a younger version of himself to fool Caitlin (so evil!). Just when Barry thinks he has Zoom where he wants him he escapes! Zoom speeds to Joe's house and kidnaps Wally.
Zoom offers a straight up trade - Wally for Barry's new found speed. The crew can't think of any way out of the situation, so they basically give up - Huh? That's the best they can do? Very weak. Wells comes up with a gizmo to drain Barry of his speed, and they give the vial to Zoom. That isn't enough for Hunter apparently, so he starts beating on the weakened Barry. Cait gives an impassioned plea for Zoom to stop - bringing up their relationship as proof that he still has some humanity left. So what does Zoom do? Well, he kidnaps Cait and winks out back to Earth 2!
I'm assuming that the breach Cisco opened is still operative, because otherwise it makes no sense that Zoom can now go back and forth. Oh well.
So now Barry must figure out a way to get his speed back AND save Cait. Let the games begin!
Another couple of things:
Iris seems to be warming up to the idea of getting with Barry: she blew off a date with her creepy editor/boss, and had a heart to heart with Cait about her possible destiny of being with Barry - so that's good.
Who is 'The Man in the Iron Mask' imprisoned on Earth 2? Given that Zoom is really Hunter and not the true Jay Garrick, could it be that Jay is that man? Or maybe a past version of Barry? Or Hunter's Dad? The possibilities are myriad!
Also, does Zoom have plans to turn Cait into Killer Frost on Earth 2? Hmmmmm.