After a skull smashes into the windshield of a teenager's car, the investigation reveals the skull has been gnawed on by human teeth, which implies cannibalism and marks the beginning of the Widow's Son case. Meanwhile, Angela and Hodgins hire a private investigator to find her husband. Bones searches for Zach's replacement and the team gets a wonderful surprise.
Benson and Stabler investigate a suspected child abuse case only to learn that the woman who reported it is the real case.
Sam Oliver has always been the slacker with no goals or purpose. However, his life takes an unprecedented new direction on his twenty-first birthday, when he discovers that his parents sold his soul to the devil and he must now become Satan's personal bounty hunter.
Patty Hewes and Arthur Frobisher continue to struggle for dominance as the deposition nears.
Relationships are broken. Repairs are needed. But that takes honesty and a steady heart. For Jen's parents, lies and deceit may end a forty-year marriage. While Cassie and Charles push each other to the breaking point (a place so far there may be no going back). All summer long Charles has been working on a special present for Cassie (a one-of-a-kind, built-with-love automobile just for her). But when he finds her in another man's arms, he doesn't wait for explanations. The two seem headed off a cliff and neither knows how to apply the brakes. Does disaster lie ahead?
Beverly Barlow returns to town just as a parasitic bacterium threatens to destroy Eureka, by turning everything to gold and then into rust --- people included.
Things are shaken up when the male beauty and the female geek finally move into the mansion. Meanwhile, the geeks are challenged to write an autobiographical rap to be performed for Three 6 Mafia, and the beauties must study politics and later put their newfound knowledge to the test while debating each other.
Sixty-five million years ago, a comet hit the earth, putting an end to life as it then was. Now a comet is about to hit the earth again. In the dramatised part of this episode, Fernando Martinez, a Mexican who works in Houston, Texas, sets off home to be with his family, the Vaton family in France seeks shelter, and the Baka pygmy tribesmen continue to hunt, unaware of the impending disaster. Astrophysicist Noah Boyle, and computer scientist Shiang Yatan, remain at the observation centre in Hawaii to try to find out exactly when the comet will hit.
Oscar's complaints about the lack of Dog River-oriented cable programming bring results, and Brent is chosen to select one show created and filmed in town. Brent takes advantage of the bribes he's getting while thinking about the shows. Wanda, Lacey and Emma can't agree on what type of show they want, while Hank finds himself the unsuspecting suspect in Davis and Karen's police show.
When the team is investigating the murder of a probation officer and a hostage situation, Horatio learns that the main suspect could be his son.
Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins showing them that as much as they know about science, they know little about actual living.
With U-Turn's timely demise Nancy and Conrad check the status on their debts and then they check in with each other. Someone is pregnant and they are keeping it. Doug continues to try to sabotage Celia and Celia continues to sabotage Nancy. Nancy celebrates something. Silas begins spending more time with Tara.
Michael and Mahone try to lure Whistler out of his hiding place. T-Bag gains some upward momentum in the prison hierarchy as the water supply is running low. Lincoln meets familiar and not so familiar faces on his quest to free Michael.
Chuck Bartowski is an average computer geek until files of government secrets are downloaded into his brain. He is soon scouted by the CIA and NSA to act in place of their computer.
Robin shows up with a date and this motivates Ted to 'get back out there'. We also learn something major about 'the Mother'.
Spencer and Heidi's wedding date gets closer, but will he tell his family before he steps into church? The Teen Vogue event gives Whitney and Lauren a lot of work, while Jason tires to start over with a new girl and a new place.
The kids escape from the Slitheen and meet up with Sarah Jane at her house. They discover that vinegar will kill the Slitheen so, armed with vinegar bottles, they return to the school and destroy the three adult Slitheen and their machine. Carl, who took on the form of the class brain-box, escapes via a teleport but Sarah Jane assumes that he is dead. Back home she accepts Clyde into the group but asks for him not to tell others about their experiences.
Maria and Luke start their new school where they pal up with another boy, Clyde. However, two of the teachers and the class genius turn out to be Slitheens in human form. They are shapeless smelly invaders from another planet whose aim is to destroy the Earth by turning off the Sun with the aid of a machine which Luke inadvertently helps them to start. The three teenagers are chased around the school by the Slitheen family.