While examining a skull, Brennan and Cam find marks on it made by human teeth, which implies cannibalism. Identifying the victim, Brennan and Booth go out to investigate, discovering a weird cannibalistic society as they try to solve the case.
Brennan and Booth investigate the death of a soccer mom who was blown up in her mini-van. They soon discover that the soccer mom, named June, was part of a group of radicals from the 70's, named the National Liberation Army.
The team investigates a decomposed body that was discovered in the woods with bound arms and missing feet. Things get kinky when Booth and Brennan are led to a lodge that's used as an S&M retreat for "jockeys" and their "horses". Meanwhile, Angela tries hypnosis in an effort to figure out her elusive husband's name so she can finally divorce him.
Booth and Brennan examine a severely decomposed body found by some teenagers on hospital grounds. They identify the body as a man named Franklin Curtis, who was the founder of an organic supermarket chain, and discover that the body was either cooked or incinerated. Booth and Brennan go out to question people around Curtis' farm, while back at the lab it is discovered that the flesh of another victim was with Curtis'. Meanwhile, Booth and Brennan are assigned to a psychologist
Mummified remains of a young girl are found in a halloween maze. Booth and Brennan go to investigate, and are shocked to find that the victim has been dead for over a year. To make the situation even creepier, a second body is found at a Halloween amusement park funhouse, again mummified, but this time dead for approximately two years. Booth and Brennan get wind of a third missing girl and link her to the person who killed the other two girls. They must now race to find the killer before he or she strikes again this Halloween.
The team suspects their own colleagues after the burnt remains of an intern at the Jeffersonian are found in the building's incinerator. At first it's thought that she might have been killed because she was working on an artifact in the Widow's Son case, but then things become more complicated when romantic ties between her and another employee at the Jeffersonian surface.
A time capsule buried by a high school class of 1987 is unearthed by a group of the school's alumni who are shocked to find the body of one of their high school classmates hidden inside. Booth and Brennan find that the victim was an outcast in high school, so they go on to investigate the past lives of the classmates in an effort to discover the murderer.
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 that of Tripp Goddard, a sexy motorcycle racer who had been murdered about two weeks ago after a race.
The team works to identify the bones of a college athlete who was crushed behind gym bleachers. After the body is identified as star player RJ Manning, they discover that he was murdered. Booth and Brennan follow several leads, at one point thinking there could have been multiple killers.
A woman's car is run off the road and she is killed, but her baby miraculously survives the accident. Booth and Brennan go to the woman's hometown to try to find out who's responsible for running her car off the road. Bones, with help from Booth, takes care of the baby until the team finds out who killed the mother.
Brennan's father Max Keenan is on trial for the alleged murder of FBI Deputy Director Kirby. Everyone on the team, except for Brennan, is called as a witness for the prosecution during the trial. Brennan on the other hand is the forensics advisor for the defense, and she must rely on both her dedication to her family and her skill as an anthropologist to help free her father.
A wannabe singer Tommy Sour is found in a grassy location. The investigation leads Brennan, Booth, and Cam to the restaurant where Tommy used to sing and where several suspects who took part in the open mike contest are, including a woman who was obsessed with Tommy and turns her affections towards Booth after learning of Tommy's death. Also, something horrible happens during the investigation which shocks the Jeffersonian team.
The Gormogon serial killer is back again, and the silver skeleton from the basement vault has gone missing. All the Jeffersonian employees become suspects, with the scary possibility that one of their own is working with Gormogon.