When Eliza confesses her feelings to Henry, he avoids the subject by focusing on the company’s annual karaoke party.

Barry finds himself face-to-face with his nemesis, the man in the yellow suit, a.k.a. Reverse-Flash, who killed his mother. Barry is frustrated when the Reverse-Flash escapes, but Dr. Wells and Cisco come up with a plan to trap him. All they need is bait, so they turn to Dr. Tina McGee from Mercury Labs to help. Meanwhile, it’s Christmas at the West household and Iris is in full holiday cheer. Eddie gives her a surprising gift but also leaves her with a question that could change her life. Joe joins the search for the man in yellow and ends up in the crossfire. Caitlin finds Ronnie.

When an ER physician is gunned down in the street, Castle and Beckett soon discover that the victim was a mob doctor to a Mafia family run by an old friend of Castle’s. Also, against this backdrop of Christmas, Esposito and Lanie reach a defining moment in their relationship.

The security breach at the Embassy has far reaching consequences.

Neal hasn’t heard from the Panthers in days and he’s worried that either Keller turned on him or Woodford simply decided to cut him out of the deal. Using the algorithm Neal stole for the Panthers, the team is able to determine that the Panthers are targeting something arriving at the San Francisco airport. But without enough time to make it to the West Coast, Peter is forced to pass on the task to the local FBI office. Meanwhile, Mozzie comes face to face with his wife, who he met on a con, married on a whim, and hasn’t seen in five years. She insists that she’s reformed and wants to start a new life (with someone new), but Mozzie isn’t convinced, and asks Neal and Peter for help.

When Alex tells Phil and Claire she has a boyfriend, they worry they’ve put too much pressure on her and has made up an imaginary boyfriend. Jay and Gloria both have parties that they are dragging the other to and Jay has a clever plan to get himself out of it, but Manny just might spoil everything. Mitch and Cam just got a beautiful white couch delivered but when Mitch is stuck helping out Brenda, a distressed co-worker, and allows her to stay – it is a mishap waiting to happen.

When Alex tells Phil and Claire she has a boyfriend, they worry they’ve put too much pressure on her and has made up an imaginary boyfriend. Jay and Gloria both have parties that they are dragging the other to and Jay has a clever plan to get himself out of it, but Manny just might spoil everything. Mitch and Cam just got a beautiful white couch delivered but when Mitch is stuck helping out Brenda, a distressed co-worker, and allows her to stay – it is a mishap waiting to happen.

Tensions run high between Clarke and Finn, while Raven discovers that Mount Weather is interfering with their communication systems. Meanwhile, Jasper and Monty discover the truth about what’s going on at Mount Weather and Octavia comes face-to-face with her worst nightmare. Finally, President Dante Wallace is about to be betrayed by those closest to him.

Mike accompanies Sue on a college tour weekend, and Frankie abandons Brick with a school project and a revolving door of babysitters while she goes to see Axl play in his first college football game.