Air date: 11/20/07

Booth and Brennan's investigation into the death of a priest leads them back on the case of the Gormogon serial killer when the priest's kneecaps were discovered to have been surgically removed. They realize the killer has a pattern for choosing victims after Angela finds a victim tree in the evidence vault. The team attempts to make predictions on who the next victim is while Dr. Sweets provides psychological insights into the killer for Brennan and Booth. Meanwhile, Brennan's brother reappears.

The Santa in the Slush

Air date: 11/27/07

Three days before Christmas, Booth, Brennan and their team are sent to investigate the death of a Santa Claus impostor after his body was discovered in the sewer near a mall. The team discovers the man's legal name was Kristopher Kringle and was highly regarded in his profession while he worked for a local "Rent-A-Santa" business. Meanwhile, Brennan and Booth find themselves under a mistletoe, and Brennan decides to spend Christmas with her father, brother and his family.

The Man in the Mud

Air date: 4/14/08

A body is discovered at Homestead Natural Hot Springs in a spring filled with mud. Booth and Brennan go to investigate the scene and find that the body is Tripp Goddard, a motorcycle racer who had been murdered about two weeks ago after a race.

Player under Pressure

Air date: 4/21/08

All team members are working to identify the bones from a college athlete who suffered a lot of fractures. After the body is identified they talk to his sister and somebody who acted as a sort of an adviser for the deceased. Zack is overwhelmed by having to reconstruct the crushed bones to form a skeleton.