Booth and Brennan Go Undercover in the Wild West on the Bones Fall Finale (VIDEO)

Marisa Roffman

Giddyup! Bones' Booth (David Boreanaz) and Brennan (Emily Deschanel) are going back undercover in the first hour of the two-part fall finale.

As the duo work to solve a murder in "The Cowboy in the Contest," the investigation takes them to an Old West-style shooting competition where they take on their undercover personas, Buck and Wanda. But enjoy the lightheartedness of the western hour while you can, because things will get considerably darker in the second episode, "The Doom in the Boom."

"The first hour is a lot of fun, and then the next episode is very dramatic," Deschanel teases in the exclusive video below. "Some serious stuff goes down." Adds Boreanaz, "It's a big cliffhanger; something that's going to leave a lot of people wondering what's going to happen next on Bones."
Check out the exclusive video for more from Boreanaz and Deschanel, including fun footage from "The Cowboy in the Contest":

Bones airs its two-hour fall finale airs Thursday, Dec. 10 at 8/7c.