On tonight's episode of "The Flash," -- "Back to Normal" -- Barry was forced to confront an adversary without his speed. Luckily he had his friends to help him and they were able to rescue Wells from a powerful meta human. Zoom also held Caitlin captive in his Earth-2 lair, while proving his love for her by saving her life from an Earth-2 metahuman. The man in the iron mask's identity was not revealed tonight, but The Flash's identity almost was, when he met up with Wally West. Each character was challenged in a different way tonight, and everyone had to learn the lesson of being able to find the hero within -- with or without speed. The end of the episode also set up an interesting parallel to "Flashpoint," which will make these last few season two episodes very compelling to watch.

Tonight's episode kicked off with Barry's (Grant Gustin) normal voice over. A sequence of images played while Barry described getting ready for work, grabbing coffee, and getting through his day as The Flash. But then the images changed as Barry had to do all those things without his speed. He had to take the bus, he had to wait in line for coffee, he even had to work on case files at the Central City Police Department at regular speed. This perspective really set the tone for the episode in that Barry now had to take his time with everything. By the time Barry got to S.T.A.R. Labs, Harry Wells (Tom Cavanagh) was leaving to go find Jesse (Violett Beane.) Harry had been desperate to find Jesse in weeks past, and since the breaches were open again, Harry didn't want Zoom (Teddy Sears) to find her first. Wells also told Barry that putting Jesse in danger was his fault, which shifted the team dynamics in an unexpected way.

Harry was able to find Jesse, but when he conveyed the danger to her and told her that she needed to come back with him, Jesse refused. Jesse was still not willing to forgive him for killing The Turtle. This scene was heartbreaking to watch because in Harry's mind, he was doing whatever he could to save Jesse's life when Zoom was holding her captive. In Jesse's mind her dad had become a murderer, someone that she could no longer trust with her life. Harry agreed to leave her alone, but he was captured while driving back to S.T.A.R. Labs by Griffin Grey (Haig Sutherland). Grey kidnapped Harry and forced him to work on a cure for his rapidly aging cells. Grey was an interesting meta human to bring onto the show this week. He wasn't after revenge or money or mayhem -- he just wanted Dr. Wells to take responsibility for the particle accelerator explosion and to help him get back to his normal age.

Back at S.T.A.R. Labs Barry, Cisco (Carlos Valdes,) and Iris (Candice Patton) tried to find Harry, once they knew he was missing. By running a DNA test and facial recognition they discovered Harry had been taken by an abnormally strong 18 year old kid who suffered from rapid aging. They warned Jesse, who came back with them, and began working on a way to find where Harry and Griffin went. While Barry was willing to confront Grey, he knew he didn't have the speed or the strength to fight him, so he had Cisco and Jesse enforce his flash suit with dwarf star alloy -- the same material that gave the A.T.O.M. suit its strength. Having Caitlin (Danielle Panabaker) on Earth-2 this episode opened up an interesting opportunity for Jesse to contribute to Team Flash in a very significant way. Jesse essentially stood in as Caitlin's scientist, similar to how Curtis (Echo Kellum) filled in as the hacker for Felicity (Emily Bett Rickards) on the Bug Eyed Bandit episode of "Arrow." Letting Jesse help solve a case was a smart move on the part of Team Flash, because for the first time ever she was treated as more then just Wells' daughter. This may provide clues as to how Jesse will fit on the team next season -- perhaps she's be Caitlin's protege.

While Team Flash was planning their Dr. Wells rescue, Caitlin was helping rescuing a familiar face on Earth-2. With Zoom gone from his lair, Caitlin was free to wonder around. She first discovered the illusive man in the iron mask. She couldn't understand his tap code or what he was trying to say. She then came upon a face she recognized: Killer Frost. Caitlin's scenes with Killer Frost were fantastic, considering Danielle Panabaker was playing both roles. Both characters were written and performed so differently, and Danielle Panabaker really soared by playing each role tonight. Through Killer Frost's persuasive nature, she was able to convince Caitlin to break her out of the glass prison cell, in exchange for escape out of Zoom's lair. Killer Frost lied of course and once she was free, she threw an impaling icicle at Caitlin. Zoom showed up and used Killer Frost's ice against her, which killed Frost instantly. It was jarring to watch Zoom actually save someone's life -- but he loves Caitlin -- and he couldn't let anything happen to her. With Killer Frost dead, that almost completely closes "The Flash's" Earth-2 story line. The only Earth-2 doppelgangers left alive are Barry, Iris, and the masked man.

The episode concluded with Team Flash rescuing Harry Wells and immobilizing Griffin Grey. As Griffin and Barry fought, Griffin kept getting older and older. He finally passed out from the rapid cellular aging. At the end of the fight his cells were restored back to normal, and he looked like a young man again. In the comics, Griffin Grey was Bart Allen's roommate. He also had superpowers that give him strength and made him age. It was great to see a Bart Allen comic book character on the show tonight, even though Bart won't be around for a few generations. Wally West (Keiynan Lonsdale) also got to meet his hero tonight, as he wanted to thank The Flash for saving his life. Wally told both Joe (Jesse L. Martin) and The Flash that he was inspired to be a better man -- to live his life for a purpose -- because The Flash gave up his powers for Wally's life. The final moments of the episode set up two very interesting storylines. First, Zoom decided that he didn't want to stay in Earth-2 anymore. With Caitlin by his side and Earth-2 already on its knees, Hunter Zolomon decided he wanted to conquer all the Earths with his speed and terror, starting with Earth-1. Jesse and Wells also reconciled, as she decided she could begin to trust him again if he promised not to hurt anyone on her behalf. Wells and Barry then decided the only way to restore Barry's speed was to recreate the particle accelerator explosion. This solution may remind readers of the "Flashpoint" comic book, where a powerless Barry Allen attempted to recreate being struck by lighting to give himself powers again. "The Flash" EP Andrew Kreisberg broke down his thoughts on Wells and Barry's plan earlier today, which can be read here.

On next week's episode -- "Rupture" -- Zoom is back on Earth-1 and Cisco is forced to go up against his own brother's doppelganger, Rupture. Barry also decides to ask both of his fathers for advice on recreating the dangerous explosion that gave him his speed. What will Barry decide?

Zoom (guest star Teddy Sears) arrives back on Earth-1 intent on taking over Central City. Barry (Grant Gustin) and Wells (Tom Cavanagh) come up with a plan to stop Zoom once and for all but it's extremely dangerous. Unsure if he should take the risk, Barry reaches out to both fathers for advice. Henry (guest star John Wesley Shipp) is adamantly opposed to Barry risking his life again but Joe (Jesse L. Martin) thinks he can handle it which puts the two men at odds with each other. Meanwhile, Cisco (Carlos Valdes) is shocked when he vibes the Earth-2 villain Rupture, who happens to be his brother Dante's (guest star Nicholas Gonzalez) doppelganger. Rupture came to this Earth seeking justice for Reverb's death. Iris (Candice Patton) decides she's finally ready to open up to Barry about her feelings for him.