The episode opens on December 23rd at 6pm. The Jeffersonian is having a Christmas party. Angela Montenegro, dressed as an elf, is trying to convince Dr. Temperance 'Bones' Brennan, her best friend, to go with her, as to keep her from photocopying her butt again. Angela then brings up the Secret Santa, to which Brennan cites she dislikes the idea of it. Angela points out rearranging Santa that you'll get Satan, and comments on how Brennan is spending the Christmas party examining a skull, making a reference to "Skeletor". Brennan relents and asks for twenty minutes, to which Angela agrees. Special Agent Seeley Booth comes in, gives Brennan a case file folder. While Brennan is looking through it, Booth gives her the details on it. A skeleton was found in a fallout shelter while the Federal Government was digging to put in a Solarium for a visiting Agriculturist. It is revealed the shelter was built in the fifties part of an A-bomb scare. Brennan remarks it was a suicide, to which Booth points out the gun and states it was one. Brennan argues that if she had the bones she would prove that it wasn't. Booth gives a whistle and the body is brought in. Brennan is reminded of the Christmas party and she asks Booth to go with Angela so she won't photocopy her butt. Booth protests but Angela drags him off to the party.
The scene shifts to Zack Addy, Brennan's Anthropology Grad Student, and Dr. Jack Hodgins. Zack is trying to control a robot with vocal command, starting with "stop" which causes it to run and then do acrobatics. When Zack commands the Robot to "turn" it stops. Hodgins laughs and remarks about the robot citing it was like Zack, "Tell it to take out the trash and it watches reruns of Firefly". Zack remarks once he fixes the voice recognition programming on the robot he'll blow those "Gomers" at MIT away. Hodgins had been making pure alcohol (the drinking kind) and had about a half liter. He plans on dumping it in the party's eggnog.
Brennan begins her cursory examination of the skeleton from the fallout shelter. Zack is doing bone scraping when Hodgins offers him an eggnog to which he declines. Hodgins takes a drink of the eggnog and Zack notes that Hodgins is avoiding a coworker because she's after him like "Alien after Predator". Then Hodgins barks "sit" at Zack's robot, causing it to run off the table it was on. Zack isn't amused while Hodgins laughs. Brennan pulls out two tickets to Paris out of the victims jacket. Booth returns and asks what she found and she informs him that they are plane tickets to Paris on an Airline that went out of business in the sixties. Brennan states that she though Booth was at the party to which he replied it wasn't a party it was a Star Wars convention. Brennan then show Booth a .22 caliber bullet pulled from the skull. Booth inquires if she had opened the suitcase which she says any information it held would compromise her objectivity. To which Booth remarks, "like a name and and address". Brennan states she likes to make unbiased initial observations. Then she spots Hodgins and Zack on the catwalk with ta clear liquid. She asks them if it was pure alcohol and Zack confirms that it is. Brennan then states that Dr. Goodman, the head of the Jeffersonian, would not let the pair near the eggnog following the "Fourth of July Fiasco". Hogins comments that they need to rethink.
Brennan then orders Zack to clean the bones causing Hodgins to laugh and tell him he got "burned". Brennan then tells Hodgins he needs to search the clothes for insect evidence. Both of the orders cause Booth to remark, "Geez, Bones. Merry Christmas." Angela then comes in and scolds Booth, and her coworkers about the Christmas party, citing that they are all going up there. She also states that she'll probably kiss all of them under the mistletoe,including Brennan but in a "festive, non-lesbian manner". She insists that they are all going to the party.
Zack is wearing a respirator mask and he tells Hodgins to put on a mask as he's going to take some core samples from the bones. Hodgins responds with an irritated "okay". As Zack starts to take the sample Hodgins takes a drink of his eggnog. the particles go through a scanner in the air vents. The alarms start going off causing everyone to pause. Booth shouts over the alarms to Brennan and Angela whom are chatting with Goodman, "what's that?" to which Goodman answers, "Biological Contaminate." The lab then locks down while Hodgins and Zack rush or the Decontamination Shower. Booth tries to get out and Angela informs him that the doors seal automatically and not to worry about it. Booth asks what she means by it. Brennan tells him that there's no use panicking until they know what it is. Zack and Hodgins, now wet and wrapped with towels come up and state that they might know what it is. Zack then states that the alarm went off after he cut into the Fall out Shelter bones. Goodman inquires if they were following Autopsy Protocol, which Zack says one of them were and Hodgins admits to be drinking an eggnog. Goodman groans after realizing that Hodgins didn't have his mask on.
The Pathogen is reveal to be Valley Fever. Which another doctor, dressed as Santa, outside of the quartine inquires if Autopsy Protocol was followed. Which it is repeated that Hodgins was not. Booth states it must "suck to be Hodgins right now, but the rest of us didn't breath it in." Brennan states that Hodgins might have breathes the spores all over everyone else, the Zack lists off the side effects of Valley Fever, which prompt Booth to threaten Zack and Hodgins with "If this is fatal, I will shoot the both of you."
The Hazmat team is called in to inncoulate the Jeffersonian team with an mix of drugs to prevent Valley Fever from manifesting. Once again Zack lists off the side effects of the drugs. None of the "Squints" are affected by it, Booth however is. Dr. "Santa" informs them that sleeping bags will be dropped off.
The team is various sections of the Lab. Booth and Goodman are in one area, comparing notes on why this would be the worse Christmas ever. Booth askes Goodman what the lights on the ceiling are, to which Goodman states that it's part of Booth's reaction to the drug cocktail. Goodman is revealed to have five-year-old twin daughters, and that he is the "Spirit of Christmas" in his home. Booth then reveals that he has a four-year-old son named Parker, and that his Parental rights are 'vague' because his ex-girlfriend has custody of the boy. Then Booth inquires again what the lights are on the ceiling. Hodgins and Zack discuss their Christmas plans. Hodgins was going to spend it with his "hot maussue" girlfriend in a cabin. Zack was going to go to Michigan to spend it with his forty cousins and cut down/decorate a Christmas tree. Then the two debate the true meaning of Christmas briefly, with both stating that theirs is right and leave it at that. Brennan and Angela are talking about 'making Christmas' for everyone. Then Angela spins a little tale about two lovers and asks "Can you imagine how she felt?" And Brennan replies, "I don't have to," after with she promptly gets back up and goes out to the platform to solve the case.