'''Airdate:''' September 26, 2010

The Griffins receive an invitation to a mansion for a dinner in their honor. When they arrive, they see that many of their friends have been invited to the mansion as well. When everyone settles down at the table, they see that their host is James Woods. At first they think he's up to no good again, but he says that he's reformed and has become a born-again Christian thanks to his new girlfriend Priscilla. When Woods leaves momentarily, Quagmire's embarrassing girlfriend Stephanie gets shot in the chest and dies. Fearing Woods did it, everyone tries to escape the mansion by driving over a stone bridge, but lightning strikes a tree and the tree falls onto the bridge, destroying it. Everyone stays in the mansion and fears that Woods might kill one of them next. When Woods shows up, they accuse him of killing Stephanie despite him saying he didn't, but then the lights go out and turn back one and everyone finds that Woods has been stabbed to death. Everyone realizes that Woods wasn't the killer and that the killer is one of them. Priscilla faints and Stephanie's body disappears.

While searching for the killer, Joe discovers that the gun that killed Stephanie was timed to go off when Woods was in his chair, but Stephanie was in it instead, revealing her death was an accident. Everyone has a motive for killing Woods, but Mort's wife Muriel becomes the prime suspect when it is discovered that Woods had blackmailed her into giving him prescription drugs. After Peter accidentally knocks out Joe while wearing a knight's armor, everyone splits into groups. While Brian and Stewie search, they hear Muriel screaming and they meet the others to discover that Muriel has been stabbed with the same knife that killed Woods, and also that the fainted Priscilla is gone was well. Jillian's husband Derek tries to help by going to the top of the mansion to get a cellphone signal and call the police, but is murdered via a blow to the head by the murderer, whose identity is not revealed, and falls to the ground. Consuela points out that one of Woods' Golden Globe awards has been stolen and used as the object to kill Derek. While the group searches Tom's room for any clues, they discover the blood-covered award under his bed. Tom defends himself by saying that Priscilla planted it there, but everyone discovers that Priscilla has been slashed in the throat and stuffed into the air duct. Tom is accused of being the killer and after a chase, Tom is captured and arrested.

The next day, the bridge is repaired and everyone prepares to head home when Lois tries to comfort Diane about losing Tom. When Diane shows Lois a shirt her mother made for her for her first solo newscast, Lois questions why she would have a shirt for the occasional already and she discovers to her horror that Diane is the real killer. As Diane holds Lois at gunpoint, she tells her her plan that she wanted revenge on Tom that because her 40th birthday had come, he had been pressuring the station to replace her with a younger newscaster, while at the same time, her romantic relationship with James Woods has died out. She met up with Priscilla when she was an intern at the station and used her as a pawn to an elaborate plan to kill those who ruined her life. She got Priscilla to get Woods to reform and invite everyone to the mansion and kill Woods with the timer, which ended up killing Stephanie instead and she killed Priscilla and Muriel simply because they discovered her in the act of fixing her plans, and Derick to prevent him from contacting the police before she framed Tom. When Lois asks what happened to Stephanie's body, it is shown that Quagmire took it planning to have sex with it. As Diane is about to shoot Lois in the backyard, Diane is shot by an unknown assailant and alls off a cliff to her death. The assailant is revealed to be Stewie, who insists that he's the only one allowed to kill Lois.

!!"And Then There Were Fewer" contains examples of ([[YMMV/FamilyGuyS9E1AndThenThereWereFewer YMMV Goes Here]]):
* AnimationBump: This is the first episode produced in high-definition widescreen with amazing use of ConspicuousCG.
* TheBadGuyWins: While she does get killed, Diane did succeed in getting Tom arrested, though he's out of jail by the next episode.
* BigDamnVillains: Stewie kills Diane at the end before she can kill Lois.
* ClosedCircle: Everyone is stranded in the mansion for the night.
* ComicallyMissingThePoint: After Diane explains her plans to Lois.
-->'''Lois:''' ''Oh my God''...you're forty?
* ContinuityNod: Quagmire points out that Brian has a grudge on Woods for ruining his TV pilot in "Brian Griffin's House of Payne".
* DarkerAndEdgier
* DisneyVillainDeath: Diane
* EvilDetectingDog: Brian growls when James Woods show up.
* HypocriticalHeartwarming: Stewie saving Lois because he insists only he can kill her.
* KilledOffForReal: The victims in this episode, [[spoiler:with the exception of James Woods]], have been confirmed to be dead and will never be seen again.
* OOCIsSeriousBusiness: Subverted. Lois tries to get Peter to know she's being held at gunpoint by Diane by calling him "Pete", which she never does. As Peter thinks it, he decides to get into the car and play music and leaves.
* OhCrap: When Lois realizes that Diane was the killer.
* TheOnlyOneAllowedToDefeatYou:
-->'''Stewie:''' If anyone's taking that bitch down, it's gonna be me.
* PsychoticSmirk: Diane when she's revealed to be the killer.
* ReformedButRejected: Nobody believes James Woods that he's reformed until he gets murdered.
* SheKnowsTooMuch: Diane almost kills Lois for finding out she was the murderer.
* SomethingCompletelyDifferent: This is a one-hour, semi-serious murder mystery special with only two (relevant) cutaways.
* TonightSomeoneDies: Four recurring characters and two new characters die.
* UnwittingPawn: Priscilla
* WhamEpisode
* YouMonster: Peter calls James Woods this when he accuses him of being the killer.