When an injunction prevents Langley Falls from lighting their annual Christmas tree, Stan blames secular non-believers for ruining his favorite holiday. With Stan's holiday spirit at an all-time low, the Ghost of Christmas Past visits him and tries to show him the true meaning of Christmas. However, Stan is convinced that Christmas can be saved by changing the outcome of Vietnam, but finds that changing the past only dramatically changes the future.

Meg can't find a date to her junior prom, and even though he is dating Jillian, Brian ends up going with Meg. At the prom, Brian gets drunk to make the night pass, but ends up making out with Meg. Meg begins to think of Brian as her boyfriend and becomes obsessed with spending every moment with him. Meanwhile, Peter, Cleveland and Quagmire join the police force to help Brian.

At Christmas time, Marge opens up her home to the jobless Gil. But problems arise when Gil overstays his welcome and Marge can’t bring herself to kick Gil out of the house.

Three passengers from 1953 arrive in modern day Cardiff, when their plane flies through the Rift. With no means of travelling back, each person must adapt to their new life, starting personal relationships with the separate members of Torchwood.