As the Griffins prepare for Christmas by decorating their tree, Meg finds an ornament of the manger and Peter tells the story of Christmas.
Joseph and his friend Robby spot Mary in their village and Joseph introduces himself to her. After many dates, Joseph is annoyed by Mary's reluctance to have sex who admits she feels like there is something special intended for her. While working with the guys, Mary comes and asks to have a word with Joseph later. At her house, Mary tells her that God has blessed her with his child and she is pregnant. She tells of a visit by an angel who told her to prepare and Joseph accepts this.
Back at the Griffin home, Peter and the family call their Aunt Helen although the call doesn't go well and Peter returns to the story.
On the way to Bethlehem, Joseph is skeptical about the baby. Elsewhere, three wise men receive a message and head to Bethlehem themselves. As Joseph and Mary arrive in town, the three wise men cross the desert. They stop at King Herod's palace for water and tell of traveling to see the coming messiah. Herod decides to protect his title by killing the child. At an inn, they are unable to get a room due to a Cher concert until Mary's water breaks.
In the stable, Mary ponders what to call the new child until the angel takes their list to God who stumbles onto an idea from the angel. The wise men argue on the way as they think they are following a plane and the doctor tells of an unsuccessful attempt with another messiah. The wise men arrive with their gifts as the savior is born. With the drummer boy, the entire group is assembled as King Herod arrives and demands the Christ child. Stewie as Jesus creates a fighter from his manger that destroys Herod's troops as Peter finishes his story. A pregnant couple arrives telling of their car breaking down and seeking aid but are given the cold shoulder by the family who threatens to call the cops.