Wanting to have the scariest haunted house on the block, Stan comes up with a ''killer'' setup; Steve competes to win the heart of his overprotective friend's younger sister.

Nucky visits Chicago for the Republican National Convention, where he finds himself intrigued by the candidacy of Warren G. Harding over more established candidates. The D'Alessio gang moves in on Nucky's territory at the expense of Eli, who has been watching over his brother's affairs. Margaret finds herself entangled in Nucky's business affairs, while Van Alden struggles with his wife's desire for a child. Rothstein prepares for legal trouble over his role in fixing the 1919 World Series. Nucky asks Jimmy to return to Atlantic City to reinforce his position.

July 1914. In London former suitor Evelyn Napier assures Lady Mary that it was Edith, not he,who spread gossip about her and Kemal. Mary counters by wrecking her sister's marriage plans with Sir Anthony. Robert is reluctant to dismiss John even though O'Brien and Thomas have obtained a letter claiming that he stole from a previous employer. Anna accompanies Mrs. Patmore to London for eye tests,resulting in corrective surgery and whilst there,discovers that John took the blame for the theft for his ex-wife Vera, a fact which Robert is pleased to hear. Thomas, fed up at his failure to get John sacked,and sensing war on the way,joins the Army Medical Corps whilst Sybil finally gets Gwen her secretarial post. Cora is pregnant, a fact which puts the proposed marriage between Mary and Matthew in doubt, should the baby be a son and heir. However,thanks to O'Brien leaving a bar of soap on the floor, Cora slips and miscarries. All the staff except O'Brien cheer William on as he beats Thomas up

Peter and Joe team up to execute a series of painful and humiliating Halloween pranks on unsuspecting family, friends and neighbors. While Brian shows Stewie the ropes of trick-or-treating, Meg sets out to attend her first high school Halloween party with high hopes for the evening.

Bo's freelance work earns her a lead on someone who might know something about her mother... but the trail ends at Lou Ann, a death row inmate who claims not to know anything at all. Desperate to prove otherwise, and increasingly convinced Lou Ann is innocent, Bo uses all her Fae connections to try and bust her out of jail. When she has to admit defeat, Bo's goal switches to one of personal vengeance: to find Vex, the Fae that framed Lou Ann, and make him pay.

In the 21st Treehouse of Horror episode: Bart and Milhouse discover a real-life board game that they must win to return home in "War and Pieces"; Lisa falls in love with a moody, preteen vampire in the Twilight parody "Tweenlight"; and Marge and Homer go on a honeymoon on a sailboat, and rescue a castaway named Roger who tries to kill them in the Dead Calm parody "Master and Cadaver".

Rick unknowingly causes a group of survivors to be trapped by walkers. The group dynamic devolves from accusations to violence, as Rick must confront an enemy far more dangerous than the undead.

Behind the scenes of episode 2