Although "Bones" will go on a brief hiatus, the CBS comedy-drama series will return on Dec. 10 with an exciting two-part fall finale where Brennan (Emily Deschanel) and Booth (David Boreanaz) go undercover to find a killer cowboy.

Booth and Brennan are dressed as their Old Western characters Buck and Wanda in a preview video that teases the first hour of the finale, which is titled "The Cowboy in the Contest." However, things get heated when the couple is challenged to a Western-style shootout.

According to CarterMatt, the synopsis for the midseason finale also teases the shocking death of a police officer.

"To solve a murder, Brennan and Booth go undercover at an Old West-style shooting competition, while Angela and Hodgins discuss the future of their family and Cam gets close with photographer Sebastian Kohl (guest star Gil Darnell). Then, the team investigates the murder of a police officer that sends shockwaves through both the Jeffersonian and FBI teams. Behavioral analyst Leslie Green (guest star Sara Rue) is assigned to work with Booth on the investigation and lends her professional assessments on who the cop killer could be, while Cam must make some decisions in her personal life and the entire team re-evaluates what is truly important to them."

While speaking to TV Guide, executive producer Michael Peterson opened up about Brennan's initial apprehension about going undercover.

"Booth is much more into the idea of going undercover than Brennan is," said the showrunner.

Brennan thinks "This is a waste of time" and just an excuse for Booth "to wear a silly cowboy hat and guns," said Peterson, adding that "She doesn't believe that it's actually necessary for the case, so she doesn't join him initially. She comes in later, but it changes the dynamic. Every other time they're basically a couple going undercover, and this time they're getting to play strangers to one another. They've been married for so long and to get to see each other in a different dynamic was a fun opportunity we wanted to take."

Although Brenna and Booth may have some fun going undercover, the other couples in the show will be confronted with relationship drama. Things will get awkward between Cam (Tamara Taylor) and Sebastian Kohl (guest star Gil Darnell) when Arastoo (Pej Vahdat) returns. Meanwhile, Angela (Michaela Conlin) and Hodgins (TJ Thyne) will face a serious challenge that will test the strength of their marriage.

TVLine's Ausiello also warned fans that one of the main characters will suffer from a "heartbreaking, unimaginable loss" during the upcoming two-part finale.

The Season 11 fall finale, "The Cowboy in the Contest" and "The Doom in the Boom," will air on Thursday, Dec. 10, starting at 8 p.m. ET on Fox.

Watch a preview video below.