Testing Jetpack features
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.
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.
Lisbon goes undercover as a prison inmate in order to get a convict to turn on her boyfriend, who is the leader of a high-end car theft ring.
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.