The Guppies try to spread the joy of the holiday season to Mr. Grumpfish.
Reese and Finch’s game of cat and mouse with Detective Carter becomes infinitely more complicated when The Machine declares that she is their newest POI.
Unable to get work done from inside the Parks Department, Leslie forms a citizen action group and fights from the outside. Meanwhile, everyone in the office brainstorms ideas for what to get Leslie for Christmas.
A friend of Jesse asks the team to help take out his boss, who has been smuggling blood diamonds into the country with the help of diplomatic immunity. Michael asks Pearce for help transferring a prisoner who may be able to provide him with information on Anson.
Leonard must face his fears after being contacted by his high school tormentor.
The study group is slowly convinced to fill in for the Glee Club at Greendale's Christmas pageant.
Nick and Hank's investigation of a dead high school teacher leads them to the school's outcast, Roddy. Nick realizes that there's more to Roddy than meets the eye, and enlists Monroe's help to get through to the troubled teenager before he exacts revenge on the students who wronged him. Meanwhile, Nick learns that his presence is beginning to affect the creature world.
Andy attempts to make everyone's Christmas wishes come true, including those of a drunken Erin. Meanwhile, Dwight and Jim are entangled in an escalating prank war wherein one attempts to frame the other.
The gang have much to prove when they attend their high-school reunion. They meet old friends and make new foes as they stroll down memory lane.
Brewster overhears the Mayor is interviewing Action Chugger about "Sky High Flyer", a film about making the most of what you have. Brewster wants to be a film maker too so offers to help the Mayor by making a film for her presentations about who puts the chug in Chuggington. Things don't quite to plan as he can't find anything exciting enough to film.
While Ash prepares for his upcoming Gym Battle with Clay, a surprise visitor with a dilemma offers both Ash and Cilan the opportunity to help!
Audrey tries to persuade Jeff to eat healthier when he is diagnosed with high cholesterol, but he can't help sneaking around with Brenda for unhealthy food. Meanwhile, Russell tries to keep up with his new college intern on the party circuit.
The team discovers the remains of a so-called "storm chaser" who seems to have died while following a tornado. But footage recorded during the storm ultimately leads them to believe he was murdered. Meanwhile, Booth becomes increasingly overprotective of Brennan both at home and in the field, and sleep-deprived Angela and Hodgins come to terms with having Angela's father and rock musician babysit their infant son.
In Birmingham, Detective Chris Anderson investigates the gruesome murder of a woman who is shot to death and then set on fire. Anderson hunts down his suspects, but it's the victim's family that reveals a final, disturbing twist in the case. In DeKalb County, Detective Joe Renaud is working the homicide of a father of four, gunned down outside an apartment complex on the east side of town. Without little to go on, Renaud and his team must put the pieces of this puzzle together to track down the killer.
Warwick seeks spiritual guidance, and following a visit to the dating agency where he met his wife, he embarks on a quest to find a new partner.
Kevin suspects that his Krav Maga teacher might be hitting on him. Meanwhile, Ruxin joins a cult in order to gain their Fantasy Football knowledge, and Jenny entrusts Andre with a secret.
As a 'Personality Greeter' is added to the staff roster, and a busking saxophonist vies for Janine's affections, Ashley realises a lifelong ambition. Meanwhile, Jerwayne finds that race can still be a barrier to love.
Ardal O'Hanlon and Richard Herring are the guests joining Sean Lock, Robert Webb and Seann Walsh.