Peter is convinced that a restaurant placemat is a treasure map. Word quickly spreads about the alleged cache, sparking a city-wide search and turning the citizens of Quahog against each other.
Peter discovers that he has a vestigial twin, whom he names Chip, growing out of his neck. It's not long before Peter resents the fact that everyone seems to love Chip more than him, so he decides to amputate his twin.
However, when Peter gets into trouble, he realizes he needs Chip more than ever.
When Quagmire meets a woman named Sonja who is as sexually insatiable as he is, he is thrilled to finally be with someone who won't judge him. However, things take a turn for the worse when Sonja abducts Quagmire, intending to make him her sex slave. It is up to Peter, Joe and Quagmire's dad to explore the seedy underbelly of Quahog to find and rescue Quagmire. Meanwhile, a love triangle emerges between Stewie, Brian and Stewie's teddy bear, Rupert.
Meg spills her lunch on the new kid, Michael, who is appropriately nicknamed "Mental Mike". When he sets the date for her end on Friday, Meg tries to get out of it.
Meanwhile, Peter continually harasses Brian in the nude until it escalates to the breaking point.
The Griffins take a trip to Italy and are forced to deal with annoying immigration laws after Peter destroys the family's passports.
When Stewie and Brian travel back to 17th century Jamestown, via Stewie's time machine, they encounter too many close calls with altering the course of mankind. Stewie decides to destroy his time machine, but immediately regrets his decision when an unthinkable event happens and he is unable to go back in time.
When Peter and Quagmire discover that their singing voices create beautiful harmony together, they form a singing/songwriting team, in the vein of Simon and Garfunkel. However, tensions run high when fame gets to Peter's head.
When Carter Pewterschmidt cancels the annual Quahog Christmas carnival, because he hates the holiday, Peter must transform his father-in-law from a Scrooge into a hometown hero in order to salvage the event.
Meanwhile, Stewie devises a master plan to get the one and only thing he wants for Christmas
When Peter finds he can't perform his, um, er, uh, manly duties, he enlists Quagmire and Joe to help him get his mojo back.
From Grimm to Griffin, three classic fairy tales get a new Quahog spin, including "Jack and the Beanstalk", "Little Red Riding Hood" and "Cinderella".
When Brian's neglected son Dylan shows up in town as a teen TV star, Brian jumps at the opportunity to be hired on the show's writing staff - instead of being a good father. Meanwhile, after Peter accidentally shoots Quagmire on a hunting trip, the two friends clash and Joe must choose a side.
After Peter's mother passes away, he forms a special friendship with her longtime pal, Evelyn, who attempts to seduce Peter.
Meanwhile, Stewie is distraught when he understands the reality of death for the first time
Peter grows frustrated when players on opposing teams continue to thank God after defeating his beloved New England Patriots football team, so he and the guys embark on a global quest to find God and ask Him to stop interfering with the outcome of professional football games.
When Chris learns that he is the heir to Carter's fortune, but refuses to take the money, Peter takes drastic measures to keep the wealth in the family.
Peter takes up smoking cigarettes, and is approached by Mr. Stone, an advertising executive who wants Peter to be the face of his anti-smoking campaign under the caveat that Peter continues to smoke.
Meanwhile, Stewie helps Chris battle bullies at school.
Brian gives Stewie an STD.
Meanwhile, Peter and the guys fight back when another group claims their booth at The Drunken Clam.
After some quality time with Stewie at the park, Peter accidentally takes the wrong baby home; to prove he's a responsible adult, Peter takes a business trip to Chicago and returns as a more intelligent and classy person.
Peter and Jerome express concern when their kids, Chris and Pam, start to date. Meanwhile, Peter pretends to be a staff member at Wrestlemania to give himself backstage access.
Meg has a surprisingly good time partying with Peter when he takes her on a college tour.
Meanwhile, Brian must learn how to live as an 'outside dog' when he's thrown out of the house after getting sprayed by a skunk.
Cleveland returns to town, but is instantly banned from spending time with Peter when Lois and Donna get into a big fight over parenting.
When Peter and Chris interrupt Stewie's TV time, the angry baby goes back in time to break up Peter and Lois so he's never conceived, but is shocked when he is reborn into a "Downton Abbey"-esque British household.