Haley is turning twenty-one and the whole family is taking her to a bar to celebrate! Claire really wants Haley to start seeing her as a friend rather than her uptight mom, Mitch and Cam make the sad realization that they may not be as cool as they thought, and Phil and Jay’s quick pit stop to pick up Haley’s gift, a new car, becomes a disaster. Back at home, Alex, Luke and Manny babysit Lily and she decides to drop the ‘where do babies come from?’ bomb.
As Abby and Jaha each try to establish their authority, Clarke comes up with a plan to stop the Grounders’ attack. At Mount Weather, Jasper, Monty, Miller and Harper plan their escape, as Dr. Tsing and Cage conduct deadly experiments.
As Abby and Jaha each try to establish their authority, Clarke comes up with a plan to stop the Grounders’ attack. At Mount Weather, Jasper, Monty, Miller and Harper plan their escape, as Dr. Tsing and Cage conduct deadly experiments.
Frankie loses her Christmas spirit, Mike unsuccessfully tries to exchange the new family Christmas tree, and a fight over Rudolph the Red Nosed Reindeer threatens to break up BossCo.
Nyssa returns to Starling City and tells Oliver that her father, Ra’s al Ghul has given Oliver 48 hours to find Sara’s killer or the League of Assassins will start killing the citizens of Starling City. Laurel is stunned when her father delivers a very special Christmas gift — her mother, Dinah. Meanwhile, Ray tries to make amends with Felicity and Oliver sets a meeting with Ra’s al Ghul.
Coulson and Whitehall’s forces meet in an explosive confrontation that dramatically alters everyone’s fates. Meanwhile, Skye discovers shocking secrets about her past.
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 Eliza confesses her feelings to Henry, he avoids the subject by focusing on the company’s annual karaoke party.
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.
