A Peace Corps volunteer traveling to Burkina Faso suddenly suffers from excruciating bouts of nausea and diarrhea from Entamoeba histolytica, and must find medical help before it is too late; a young woman almost suffocates due to hantavirus pulmonary syndrome she got from breathing dust while cleaning up contaminated with mouse feces; an 18-month-old boy gets infected with Baylisascaris procyonis worms which cause his brain to swell and have neurological damage, eye fluttering, and unresponsiveness.
Mel's sister, Meredith (Jaime Pressly), comes home from prison on furlough to celebrate Christmas with the kids and Mel, and seems unruffled by Joe's obvious animosity towards her. Note: this episode is a Christmas special and was only put in after EP15 because it was near Christmas. Episode 15 ends on a cliff hanger and is continued in episode 17.
It's Joe's 69th birthday and he's never flown a helicopter before. So Mikey plans a special gift of chopper flight lessons, complete with surprise pickup in front of the Buffalo hangar. Mikey jumps in for the ride as Joe struggles with the unfamiliar beast – and both McBryans will learn if they've finally found an aircraft that Joe can't master. Another cold snap has cut off heat and power in a small northern town. AJ and James battle a frozen engine before they can head up with a load of supplies. On the way home, an engine fire forces the crew into an emergency shutdown.
When a man is found murdered at an elaborate holiday party complete with real snow and live reindeer, the CSI team is brought in to investigate.
Bugsy reveals a plan that will transform the city; Bugsy uses violence to prove a point; the police force scours the city for leads; Jasmine struggles to stay out of harm's way.
When the BAU is called to Kansas City to investigate a series of murders, a tense reunion ensues between Blake and her father, a retired police captain, and her brother, a detective, who must work together to help solve the crime.
Cordelia’s attacker is revealed. Fiona looks to form an alliance with Marie Laveau. Nan learns a disturbing truth about Luke’s past.
After covering from a near-fatal drug overdose, Oliver begins hallucinating people from his past. Believing he's a liability, Oliver gives the information he has on Cyrus Gold to Quentin... which results in the deaths of several police officers. Meanwhile, Brother Blood captures Roy and uses him as a test subject for his new serum. In the past on the island, Ivo gives Oliver an impossible choice to make.
Jay takes Manny out to cut down their own Christmas tree, and Gloria is on edge with mom in town, but changes her tune when she sees her bonding with Claire. Elsewhere, Mitchell is forced to do last minute shopping when they didn’t get Lily the right gift, and Cameron takes Lily to a charity event where they experience the true meaning of Chritmas.
When Wendy tries to prove a point about how much pressure little girls feel to look like celebrities, it gets her in trouble with everyone at school, and gets Clyde a new girlfriend.
Jack's secret is revealed, but he's still not yet broken the news to Sarah: the race is on before she finds out! Meanwhile, there's plenty to celebrate at a relaunched Swayze's.
Sad news inspires Alan and Celia to have another wedding ceremony for family and friends; Caroline and Kate spend a weekend away, but it doesn't go as planned; and Judith causes trouble between Gillian and Robbie.
In a shocking cliffhanger episode, Coulson takes the war back to Centipede, and this time he brings in Michael Peterson for some super-soldier support. As they get closer to the truth, startling secrets are revealed and an unexpected twist threatens the team.
Tickle bootlegs at night, while Wayne comes up with an ingenious drop-off plan for his own bootleggers. Equipment failure threatens the production of Tim Smith's legal moonshine, and Josh and Bill finally begin their first run of strawberry brandy.
All seems lost with firehouse 51 on the verge of closing its’ doors, thanks in no small part to Gail McLeod, but Chief Boden and the rest of the house refuse to allow themselves to sit by and let it happen. An emergency call to an apartment structure fire tests everyone’s limits and puts the squad in harm’s way. Meanwhile, Dawson receives some life-changing news and union president Greg Sullivan makes headlines, which has an immediate impact on Mouch.
The ramifications of Jax’s choices put his club and family in jeopardy.
Pete, Kate, Diane and Jackie wake up Christmas morning hung-over and the house in complete disaster. They try to piece together the events of last night’s Christmas Eve festivities while also trying to save Christmas for the kids.