Annie, Kay, and Dennah are able to convince Jake that Gil has become too reliant on him. Jake wants Gil to take charge of his own life but things end up changing the balance of the entire group.
Alaskans stockpile necessary supplies for the coming months with winter quickly approaching.
How Albert Einstein thought he had found the fatal flaw in quantum theory, because it implies that sub-atomic particles can communicate faster than light.
Anders is participating in a dog sled race. He asks Jett to join his team and Jett agrees. Also, Jett learns mushing words, like "Hike!" (get moving). However, after taking a small lead, the dogs gets distracted by an arctic fox. Therefore, Jett and Anders went off course and do not know where they are. On top of that, Jett's heavy jump on the ice created an ice floe, where they cannot escape and are going out to sea. How will the both of them finish the race now?
As the Kennish and Vasquez families prepare to celebrate Christmas in their traditional ways, Bay and Daphne find themselves living each other's lives as if the switch never happened on an all-new holiday-themed episode.
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.
Kristen reveals that Tom Schwartz may be cheating on Katie. Katie interrogates the SUR staff about Schwartz's infidelity and discovers they know more than expected. Lisa hosts the "50 Gay Mayors" event at PUMP.
It's a race against time as the Monkeys rush to finish the KITT car. Richard's on edge because he's worried that he and Aaron might not make it to the Las Vegas birthday party with the car by the deadline. They also don't know if the Hoff will show up.
When an old friend of Richard's offers him , for a Knight Rider KITT car and a bonus if he can get David Hasselhoff to appear at his th birthday party, Richard can't pass up the offer. He sets out not only to find an 's Trans Am, but the Hoff.
When an old friend of Richard's offers him $200,000 for a Knight Rider KITT car and for David Hasselhoff to appear at his 40th birthday party, Richard can't pass up this offer. He sets out to not only find an 80's Trans Am, but the Hoff.
Some shocking secrets are revealed by Rafael and Jane. Petra discovers another way to complicate Rafael's life.
When Sylvester accidentally triggers an explosive device during an investigation, Team Scorpion must focus on finding who's responsible even while their friend's life hangs in the balance.
An old heartbreaker flame of Toast's, Lorna Wynde, turns up in London, but is she still in love with him, or is she trying to make her husband, Josh Homme, jealous?
Crabtree and Higgins go under cover to investigate the murder of a vaudeville comic.
When the Slotter's miners and Ling's railway workers fight one another to control the mine, the women take sides resulting in loss on both sides.
Daniel's running the store when head office announce the canteen is no longer free. The staff are not impressed so Charlie takes them all out to lunch to take the heat off Daniel.
The team become involved in an investigation into the murders of Marines whose sons are at military academics.
Brandon looks back on Callie and Jude’s first Christmas with the Foster family.