On The Flash, Barry comes face to face with the Reverse Flash -- the man who killed his mother! When he escapes, The Flash Team works to bring him back in.
It's Christmas in Central City!
One day earlier, Barry and Joe are decorating the tree but Barry thinks it's going to slow and flashily decorates the tree. Joe doesn't want that so he undecorates it just as quickly. He gets called into the precinct just as Iris delivers egg nog and rum.
Barry and Iris exchange gifts. He gives her a replica of her mother's wedding band on a necklace. She gives him a microscope and then Eddie arrives.
Barry takes gifts and egg nog to STAR Labs. Harrison is depressed because he's reminded of the accident.
Eddie asks Iris if Barry likes him. Iris thinks it's crazy. Eddie gives Iris a key to his place in a ring box.
Caitlin sees a man on fire in the garage. By her reaction, it seems she may have recognized him as Ronnie.
Men in a lab see a blur and he kills a few dudes. Barry is excited the blur is back and Joe admits he's known for a few weeks. Barry is shocked to learn of Joe's run in with him and the threat to Iris.
Joe shares information with STAR Labs about the blur. Mercury Labs is where he hit. Dr. McGee has developed prototypes for the future of something with tachyons (?). It can make someone invincible. Harrison, Caitlin and Cisco start creating a trap.
Caitlin heads to Jitters. She's wondering about the burning man Iris wrote about on the blog. Iris takes the opportunity to ask Caitlin if Barry is keeping something from her. Caitlin thinks she should just ask.
Dr. McGee checks in with Harrison and Barry at the police station. She can't believe Harrison is helping the police.
Caitlin shares her suspicions about Ronnie with Cisco.
Flashback to Barry and Nora on the night she was killed. Barry is in front of his murder board remembering it all. Iris drops by, noticing his mom's case. She never knew he looked at it all the time. She shares the news about moving in with Eddie. They've been together a year. Barry is rather crushed, even when Iris says Eddie thinks he likes her.
Barry looks outside his window. The man in the yellow suit is across the street. He runs out to the blur. It taunts him and Barry chases him to a stadium. They start fighting, Flash style. The man in the yellow suit is much faster than Barry. Yellow keeps telling Barry they've been at it a long time. It's his destiny, as it was Nora's destiny to move.
Barry recounts what happened. Harrison wants to help him catch the blur. Barry worries he cannot catch him since he's so much faster. Barry won't stay behind. Not today.
At the precinct, Dr. McGee does not want to give them her tachyon prototype. Barry threatens to reveal everything he saw in her lab at Science Showcase Magazine would like to hear about. She agrees to give him the device. Is saying Barry is a lot like Harrison to be telling?
Eddie tells Joe he better be included in the search for the yellow dude in his own quest to get the Flash 'cause his task force rules. He'll tattle if Joe balks.
Caitlin and Cisco search for Ronnie. They find him. He keeps telling her she is not Ronnie. She holds his hand and then he goes up in flames at the thought of going back to STAR Labs.
Barry is angry Joe and Harrison want to leave him behind in their search for the blur.
Caitlin and Cisco talk about Ronnie. She used to play a game wondering what she would give to see Ronnie for just one more minute. Now she wishes that day had never come and he had died that day.
Barry visits Henry at the prison. Barry tells his dad he screwed up. He found the man who killed mom, he's out there and he had him, but he got away. Barry cries at the thought his father is in there because of him. Henry knows every decision he's made in the past 14 years has been because of him and Nora. Even staying away from Iris. He wants Barry to let him go. The man in the yellow suit has taken enough from their family.
Barry arrives home and Iris has finished trimming the tree. Is he alright? Barry tells her he loves her. Really loves her.
Cisco is looking for the tachyon particles with their trap. They trap the man in the yellow suit. Both Eddie and Harrison are in the room with the thing. Eddie is scared shitless. Joe wants answers. He ignores Joe and addresses Harrison. They meet at last. Harrison wants to know why he wants the tachyonic particles. Yellow says his goals are beyond Harrison's understanding. Harrison disagrees, he's pretty smart.
The barrier starts to crumble and Cisco doesn't turn it off. Harrison is inside and Yellow is pounding the crap out of him. Joe breaks the barrier with a baseball bat (that wasn't very hard to do) and Yellow is zipping around the room throttling people, Eddie and Joe included. The Flash comes in. Yellow tells Joe he warned him not to hunt him.
The Flash and Yellow are in an incredibly epic showdown even going airborne. Barry loses his hood and gets knocked out. Ronnie drops by takes Yellow down. When he rises, Yellow says, our race is not yet done. See ya soon, Flash.
Ronnie tells Caitlin not to look for him again.
Joe and Eddie talk about what happened and Joe shares the information on metahumans.
Harrison is upset he wasn't told Ronnie was alive. Caitlin takes the blame. She wanted to see if she could make him whole again. Harrison doesn't know what he would have done differently in her situation. He promises they will bring Ronnie home.
Barry is looking at a snow globe in front of the murder board. He talks about Nora's travels around the world. Joe reminds him how he offered to send Barry abroad in college. They have one of their touching moments.
Back at the house, Iris is sitting on Eddie's lap, but Cisco and Caitlin are there to take the edge off. Barry tells Iris and Eddie he's happy for them.
Cisco talks to Joe about the red and yellow lightning. There were two flashes in Barry's living room the night Nora was killed. He puts the angel on the tree and Iris looks back at Barry.
Harrison is in his special room. He has a ring with a lightning bolt on it. He puts his fist on the wall and reveals the yellow suit behind it. That bastard! He needed the Tachyon stuff to complete his suit.